Most any aftermarket piston will have plenty of clearance...

...even for .650" lift and a little more. However, valve events and LSA's can make a big difference, so never take anything for granted, even when someone else with the exact same rotating assembly and head package has no issues. Like you say, there are plenty of variables.

Unless the pistons are hanging out of the hole for some reason, I always check P/V clearance with no head gasket...then you know you have .040-.050" of "cush". I use some clay and a dial indicator with checking springs.

The clay lets me see the radial clearance in the valve relief. The dial indicator and checking springs let me use a degree wheel and map out the clearances based on BTDC/ATDC maps. The exhaust valve clearance will almost always be the tightest around 10° BTDC, because the piston is chasing the exhaust valve down. The intake valve clearance will be close at around 10° ATDC, because the valve is opening and is trying to chase the piston down...

Brent Lykins
B2 Motorsports, LLC