The pistons are Sealed Power cast units for a 307. The 250 pistons from Sealed Power actually had a lower compression height!

I realize this is an inliner site, but to be brutally honest if I wanted to build a incredibly powerful engine I would go with a LS-style of engine. I actually have a 6.0 LS style engine that would push over 400 HP just by putting a regular carburetor on it, stock everything else! I am building this as "budget" as possible, except for certain areas where I can have a drastic (IMO) effect by spending a slight bit more, like roller rockers, multi-angle valve job, lump port, etc. Things that will directly affect efficiency. If I can get 9:1 compression with the cheap pistons (under $20 a piece) it isn't worth me spending bigger dollars to get it to 10:1, which is probably my limit on pump gas. I'm sure some will disagree with me, but that's just my thinking!