Stock 400 Piston Boost

Well, that link to Richard Holdner has many dyno tests that are pressurized engines. The big thing is the ring end gap. If the engine starts its life with you having a good leak down test, then it’s just ring gap issues to address.

Being a cast piston and low boost, a thing done over and over for decades, you’ll have no problem. The big power at low boost (5-7 or so) is the same as a well working NA engine. Easy breathing in, easy breathing out will make more power and possibly lower the boost pressure while your at it.