The pic of the witness mark in that one piston is way way off.
Are the other witness marks located in about the same place?

I have sold several stroker rotating assemblies with Icon pistons, no reports of any v/p clearance issues.
Big variety of heads have been used with them.

Since these aren’t motors I’m assembling, I don’t know how thorough the mock up and inspection is.

I saw this pic posted a while back......
440 Source 512 low deck kit, Indy 440-1 heads(bigger ex valve than the TF head).

From what I can tell by judging this one pic...... at least from this angle...... it doesn’t appear that the exhaust valve is centered in the pocket all that well(but I def wouldn’t consider it a definitive answer), but the valve doesn’t seem to land outside the pocket.