Andrew Mace said:
I'll wager almost as many didn't and would still have factory-original components.
Well, I wouldn't care to take either side of that bet, Andy. But so far, the majority of TR3/4 engines that have come my way have not had the original liners in them. There was one TR3 that did appear to have 3 of the original pistons in it, but it was a low mileage car (with extreme rust issues). TS39781LO already had 87mm liners in it when it came to me in 1984 (and needed them replaced), as did the TR3A my Dad bought back in 1974 or so (don't know the engine/commission number offhand, but likely somewhere in the TS50k range). Ditto the wrecked 3A I bought for parts around 1982. The TR3A I had before that might have had the original pistons & liners in it, but was grotesquely worn out (bearings worn into the copper backing); and as I recall, an 87mm liner set was actually cheaper than just replacement pistons & rings. (At the time, JC Whitney carried the liner sets, but not the individual components.)
I've not been into TS13571L yet, but from the way it runs (and the PO's statements), I'm confident it has been updated as well. It may even have a bit of a cam in it, as it tends to lope at idle for no apparent reason.