AB07 inlet valve & piston clearance question

I have spoken to Kent regarding the clearance and this is the info i was given - what i was asking was did they produce this cam with clearance on skimmed heads and here's the info i was given:

9 thou (1/4mm) TDC and 2mm valve drop

So from the info i was given what would be the last size head it would work without pockets?

I run standard Cosworth pistons and a Grp A gasket