Cast iron head compared to alloy head

[my way]

Eye browing flat top pistons for the classic in lines head I don't have yet. using stock cast iron head, the angle of the valve looks like 10 deg. and the spacing cent to cent about 1.793?? Are the valve locations and angles the same?? That is, can I relieve the piston for the cast iron head allowing for the bigger valves and have these pistons work for the alloy head??
The alloy head is back ordered and have been waiting on most every thing I need for each successive step
My way

 

[drag-200stang]

Do you have information that clearance is needed.

 

[my way]

Do you have information that clearance is needed.

Don't have the head yet for measurement, but----About .035 quench with CI Clay Smith 292 -108 LC .495 lift gonna have some valve lift on overlap at TDC. Comp will be up there even with 3-4 cc for valve pocket so want some safety factor for possible high lift rockers or different cam.
Truth of the matter--not sure
My way

 

[drag-200stang]

On a log head I have run 1/8 inch pop up pistons with .020 deck, .070 off head and .020 shim gasket. With a 292 degree cam at .500 lift. the valves were not close at all. I would wait till you get the alloy head and then check.

 

[rbohm]

On a log head I have run 1/8 inch pop up pistons with zero deck, .070 off head and .020 shim gasket. With a 292 degree cam at .500 lift. the valves were not close at all. I would wait till you get the alloy head and then check.

^^this^^ dont make ANY changes until you have physically measured the v/p clearance, and know exactly what you need. as we say in the racing world, only change what you have to change, and even then make sure you have to change it.