I would say the engine was stamped at Meriden - the background Triumph logos look regular (not stamped by someone with a logo stamp
) and the "T140V" looks like a standard block stamp, its letters and numbers look regular.
If you want to check if the right hand crankcase started out with the left hand one, look at the bottom engine mounting - each crankcase half should have a code (not the engine number) stamped on it; if the code is the same on both halves, they started out together.
Engines were stamped with their complete "engine number" (model code, date code and five numbers) when they were completed. Frames had the complete "engine number" copied on to them when the engine was installed. Based on that and your bike's frame number is higher than the engine number, I would say the engine was probably built in July (H) 1976, near the beginning of the 77 model year (P) - the original bike with the frame date code PP was assembled in November 1976.
Your frame number is less easy to decipher from your photo. I would have expected the "T140V" is a block stamp also, other letters and numbers stamped individually so straight and level is not expected. However, if the "T140V" characters have also been stamped individually, an originally unnumbered frame might have been stamped to match a title document someone had, either because the original frame was damaged or simply to assemble a saleable bike from a collection of parts.
There are not many differences between the twin carb T140V and contemporary single carb TR7RV. If the p.o. did not intend to use standard airbox parts, single carb head is all that is required.
As your engine is most likely 77, there would originally have been a hole through the crankcases for the "Foot change spindle" (parts book "Chaincase and Chains" pages, part #20), that connected the original left hand shift lever to the gearchange mechanism in the right hand outer gearbox cover. When you remove the primary cover, hopefully you find the hole blocked.
It is possible the p.o. wanted a right hand shift. Or, see the "Foot change spindle" has a U shaped part, this cleared the original chain driven clutch but might not have cleared the belt drive clutch.
Your photo with that appears to show the frame plate behind the engine has had a large hole bored in it? Possibly for the brake lever pivot?
I cannot be sure from your photos whether the bike has a disc brake swinging arm (correct for 77) or a drum brake brake swinging arm (correct for left hand brake)?
It is possible to use an internet search engine to find parts, usually with photos. If you enter "triumph 83-2513" (drum brake swinging arm) and "triumph 83-7035" (disc brake swinging arm) into an internet search engine and study the returned photos, you will see the primary difference between the two is the location of the brake torque anchor - drum brake swinging arm has it near the pivot under the left arm, disc brake swinging arm has it near the axle slot under the right arm.
If you disconnect the brake rod and rotate the brake plate anticlockwise until the lever is at about 12 o'clock, either the torque arm lug or the hole for it should be visible at about 6 o'clock.
If you decide to continue with fitting a drum rear brake, lever, etc., you will need one of
74,
73,
72 or
71 parts books for the part numbers.
