I would do the clay test for piston clearance.
As diameter increases, valves get closer to the piston.
I would do a temporary test fitting in a head from the junkyard
to check for interference with valves next to each other.
Unless you open the ports all the way down to the valve seat,
you might not be helping yourself that much for what it costs.
Look around an see if this is sold ready-made by anyone.
If not, then maybe people don't do it; for a reason......-Bob