Check My Cam Degreeing
I am certainly capable of using an exhaust by mistake. lol
And so are we all! LOL Juuuust checkin'....
Good deal on the open chamber area depth... .070" deep jives with the chamber volumes that you reported on those 915's, and both numbers are consistent with the notion that the heads have been milled about .040". With that new head gasket and all the other dimensions, I am thinking your gap from dome to open head area will be around .040" and that would be great. You'll have a good quench/squish gap to help reduce tendencies towards detonation with that higher CR and iron heads. Plus it helps combustion overall and efficiency, etc.
IMHO, do that clay test at all 4 corner cylinders of the engine to try to catch any spot that might be tighter than the others; the decks can slope front to back and so on. And, then check the dome height out of the block on each and every cylinder, as well as the open chamber depths. You don't want a longer-than-average rod or an offset crank throw to close that gap up too much. You're getting that piston-to-head gap snugged up nice and tight but you don't want to get too tight anywhere.
Your piston-to-valve clearance will change a bit if the cam timing is changed, so yes, be thorough and re-check.. But with what you had before, and the cam profile, it is very probably gonna still be fine.
