Del,
There may be a slight problem with taking the mopar flattie out to .125 o/s. They have a very thin, replacable sleeve pressed in the bores. The maximum overbore on the sleeve is .060 after that it gets too thin to dissipate enough heat to hold up.
At first thought, I was going to eliminate the sleeve and overbore the block to really open up the bores in these engines. However, the block casting is really too soft to withstand that type of duty. Flat Ram made mention of engines wearing out very prematurely and I attributed that to either a sleeve bored too thin or running the block unsleeved.
All hope is not dead! I haven't tried this but have read about it. Some antique tractors are dry-sleeved and have the same soft cast problems as the mopar. The blocks have been "cryogenicly" treated to harden the surface of the cast much like "case hardening". The difference is that the machined dimentions are not distorted as in the radical introduction of heat. Cryogenics is a deep freezing of the block in liquid nitrogen to achieve the same net effect as the cooling phase of heat treating.
I don't think I'll ever go this far with the mopar as the overall increase in cid wouldn't be that great as with the tractors, achieving in some cases as much a .625 in additional bore diameter.
Hudson
