Really not 100% sure if you mean Hemi or Wedge since both blocks were made from that common casting.
It seems more of a Hemi question since that's the only one with round 4.25" chambers, but maybe you were talking about a 906-452 kind of a thing since they are nearly round, sort of?

Most Wedge stroker configurations make plenty of compression with a flat piston.
You adjust clearance with gasket + machine work/deck height of the block/how far in the hole they are.

Most 4.500 Hemi pistons....more accurately the ones that I have seen (only a half dozen or so, so not very many TBH)
are flat around the outside edge (as shown) to get around any issues. That being true, then the deck height/how far the flat area is in the hole + gasket
also creates your clearance right there.