I have only scanned the replies but runs great cold runs poor hot to me sounds like it could be too rich. Can you borrow an exhaust gas analyzer? A LM-1 or LM-2 with one of the adapters to put into the end of the exhaust pipe might tell you a lot.
It sounds like you have done a lot of hard work with little to show for it. Immediately jumping to the pistons are too tight when hot seems like a big leap when there can be so many other reasons for a car to run poorly when warm. What was the coolant temperature when warmed up? If the pistons are that tight I think cutting open the oil filter and looking for a cubic shitload of metal would be a step to take.
I had a MSD Blaster 2 coil, lasted less than 6 months on our 70 Road Runner. Replaced it with a Lucas sport coil and it has worked great ever since. Until the rear frame rail cracked, the boot lid fell off and the rear window fell out but that is not the fault of the coil.