Put the head on with the rocker boxes already on…..
Took the head off and removed the rocker boxes.
Put the head back on and tried to install pushrod tubes….
Took the head off and installed pushrod tubes and then the head….hand tightened bolts…
I’m learning…. Lol
Given the history you have posted previously, have you replaced the tappet guide block O rings (1972 T100 parts book pages 22/23, part #3 E7563)? Tappet guide blocks are in the bottom of the cylinder block between the cylinders; be aware a failed tappet guide block O ring will manifest on a running engine as an oil leak from the area; to fix, you will need to remove everything down to the top of the crankcases ...
If you have not replaced the tappet guide block O rings, I advise the factory removal/installation punch tool 61-6008, it is inexpensive for its convenience.
If you have not done so already, removing the cylinder block will allow replacement of the gasket between it and the crankcase, this gasket could have dried out while the bike was unused, another potential oil leak. When replacing this gasket, I advise either a reusable copper or aluminium one or a Covseal - if you are not aware of the latter, the material is an aluminium-rubber sandwich devised by US Triumph parts wholesaler Coventry Spares, because Triumph was not great at ensuring parts mating surfaces were parallel, and even many of those that were have not always had the most careful owners/mechanics ...
Removal of the cylinder block and base gasket will also allow you to inspect the top of the crankcase joint - Triumph did not always ensure it was flat

although a 'step' here is another leak on a running engine ...
Turning to the pushrod tubes, are you aware the 72 T100 parts book does not show/list all the pushrod tube parts possibly required? If you were not, use
one of the TR5T books (mostly the same engine) and the following modern upgrades:-
. Both the 72 T100 and TR5T parts books (actually all 71 onwards 500 parts books) show different O ring part numbers top and bottom of the pushrod tubes. Modern upgrade here is to use E11283 (71-1283) both top and bottom - the O rings are the same size, the reason for the different part numbers is E7310 is Buna-N (usually? coloured red) whereas E11283 is superior Viton (usually? black). If you ordered E7310 from a good parts dealer, he should have substituted E11283 already.
. The TR5T parts book shows an additional seal - part #57 and 70-3547 - and retainer - part #56 and 71-1707.
. In addition to two (or more) 70-3547, I advise having two (or more) of 70-4752 on hand. Both are the same inside and outside diameter and
if necessary fit in the same place - one around each tappet guide block under each pushrod tube; however, while 70-3547 is approximately 1/10" thick, 70-4752 is approximately 1/8" thick.
Then welcome to the minefield, note "if necessary" above ...
Not mentioned in the workshop manual is the need to check the 'crush' of any 70-3547 or 70-4752 seals fitted when the head is torqued down.
The background to this is Triumph changed the pushrod tube sealing from 69. However, the change was not tested properly - whether or not the new for 69 O rings top and bottom of the pushrod tubes were pressurised correctly to seal properly depended on the accurate machining of cylinder block, tappet guide block, pushrod tube and cylinder head; there are always tolerances but, given so many parts, the seal to prevent oil leaking was not always achieved.
Triumph's 'fix' was to fit an additional 70-3547 or 70-4752 seal between the bottom of each pushrod tube and its tappet guide block. These seals were 'on the shelf' as they had been used to seal (different) pushrod tubes before 69 (and the triples always used 70-4752). The snag with their use on twins after 69 is, as I say, 70-3547 is approximately 0.100" thick and 70-4752 is approximately 0.125" thick, while they need to be 'crushed' when the head is torqued, even Triumph said the 'crush' should not exceed 0.030" but, even on a bad day, the total tolerances in a given assembly of parts were never anywhere close to the remaining 0.070"-0.095". 'Crushing' a 70-3547 or 70-4752 seal too much can actually cause an oil leak and, when other parts cannot be 'crushed' any further, then torquing the head bends it over the pushrod tubes ...
So it is wise to "check the 'crush'", especially as you have just had your bike's head refurbished ...
There are various check methods in internet forums but one of the easiest I know is simply: fit pushrod tubes with O rings but without either 70-3547 or 70-4752, two copper head gaskets and the cylinder head, note any vertical movement possible in the pushrod tubes, hand tighten the cylinder head bolts into the block then note how much of the previously noted vertical movement remains.
Reason for "two copper head gaskets" is they should be a similar thickness to the desirable 0.030" 'crush':-
. i.e. when the engine is assembled and torqued with only one head gasket, the thickness of the removed gasket represents the amount of 'crush' that will be applied to the pushrod tube seals;
. test-assembling with the two gaskets, after hand tightening the head bolts, any remaining vertical movement in the pushrod tubes represents additional seal thickness that must be added between the bottom of each pushrod tube and its tappet guide block.
If an additional seal is required between the bottom of a pushrod tube and its tappet guide block, 71-1707 is required as a retainer. In addition to modern ... mmm ...
variations ... in parts quality, aiui even Triumph made at least two versions of 71-1707, with slightly different inside diameters, because it must be a sliding fit over the bottom of the pushrod tube but the clearance cannot be excessive or it cannot prevent the seal being extruded when the head is torqued.
Installed the clutch side cover and tightened…. Found a long slender threaded tube… took the cover back off and figured out the cover has to be on to install the long slender nut for the chain tensioner…
Possibly ... cover fitted before primary chain Adjuster sleeve nut, I have never been able to 'start' the sleeve nut on the Tie rod thread - the sleeve nut is a close fit in the Chaincase and there is not sufficient 'wiggle room' for the sleeve nut to pick up the end of the Tie rod lying in the bottom of the Chaincase hole.
However, if any compression is applied to the Chain tensioner blade, also the Chaincase cannot be fitted ...

I have always screwed the sleeve nut on to the Tie rod up to the tensioner blade, fitted the Chaincase then adjusted the chain. Btw, another useful but inexpensive tool, for turning the sleeve nut inside the Chaincase. is either 60-3961 or 61-7012 - same tool, first number has a knurled end for fingers, second number has a hex end.