I added a 850 TQ, performer intake, Hp manifolds and a Lunati 60302 cam to a stock compression 74 400 2v and I'd say it "feels" like 300 horse or so now. Keep in mind it's in a 4500lb 73 New Yorker with 2.76 gears so it isn't quick but from a roll it moves ok for what it is.

When I had the heads off the pistons were about .090 in the hole.