Originally Posted by oldbogie
You need to find a machinest that at least stepped into the last half of the 20th century, let alone has a knowledge base in the 21st.
As for a 100 bucks more here and there, that sounds like the line attributed to Everett Dirksen in a speach on the US Capital floor somewhere in the mid 1950's where he is said to have said "a million bucks here, a million bucks there; pretty soon you're talking real money". It is non-the-less a trueism where building engines is concerned.
I'm thinking just a plain old set of moly rings with the correct thickness for the piston ring lands will git 'er done for ya. Im not so sure the rings you have won't work, but I appriciate you're concern about the effort to fix it if they don't. If the pistons are hyper-eutectic castings or high silicon forgings and your machinest clearanced them correcctly (tight) for this material even the low tension rings should be fine. But given the torque plate error I guess there's no reason to suspect this would be correct for these high silicon, highly temperature stable, modern piston materials either. You can at least measure this to find out.
Op if you have dail bore guage that reads ten thousands of an inch. If the guage reads the bores as dead straight and round they are as good as they come from the factory if not better.
If the bores have already been smoothed over for his other rings wont the cast and moly ring combos not seat into the block right. Since they still need that first cut in to really seal up like factory. This was my first thought as well but wasnt sure it would last as lng as just running the rings he has and hope the machinest did a good job.
@Engineczar i think its a ford 347 alot of builders use low tension compression rings as well. I know most chevy applications with low tension are only for oil ring but really not sure. Just had some issues with fords low tension rings and lots of blow by with big turbos.