Me thanks some thing has gotten lost in the translation between your engine builder, piston maker and you and us
Is he wanting to use a quench dome piston instead of a flat top with valve releifs
Your not saying what C.I. your motor will be but my first pump gas 505 C.I. 400 block stroker motor had to have 22.0 CC dish piston at .025 down in the cylinders to have 9.25 to 1 compression ratio with 84.0 CC heads
I had a set of large valve ported and polished 906 iron heads on that motor originally and later swap them to a set of Eddy RPM with 84.0 CC heads, the compression ratio stayed the same so I ended up swapping out the 4.25 stroke crankshaft to a 4.300 stroke crankshaft the next winter to raised those dished pistons up to zero deck to get 10.3 to 1 compression ratio.
Most of the pump gas stroker motors I build now have a reverse dome (half a dish) pistons in them with around 10 to 14.0 CC to get 10.4 to 11.0 to 1 compression ratio to run with aluminum heads on the street on pump swill