What's a reverse dome piston (small block)?
A reverse dome piston(aka dish piston) is concave into the surface of the piston. Literally the opposite of the dome. This can be for valve clearance or to keep compression manageable on a small chamber head.
Note that many piston mfg's "incorrectly" identify positive or negative cc's.
A dome should be negative cc's because it makes the compression chamber smaller.
A dish (aka reverse dome) adds cc's to tje combustion chamber
