1972 Demon 340 engine mods

His Mopar is a '65 Barracuda. I own the '62 Dart shown in my avatar. That road course looks like a lot of fun!

OK on the new owner's intended use; that confirms that you want to keep a wide torque band. His use is more like rallying.

If the engine has high compression pistons, then everything changes. The top of the original high compression pistons are above the block about .018" at TDC, instead of being about .080" down in the block for the low compression pistons. But the pistons could be different from either of the original stock types if the engine was rebuilt.