It's a procedure all competition engine builders use. On the "overlap" at the top of the exhaust stroke, put a dial indicator against the intake valve spring retainer and use a pry bar to push the valve down against the top of the piston. Start about 20-30 degrees of crankshaft rotation before the piston comes to the top and repeat the check every 5 degrees as the engine rolls over center. Record the readings. Then move the cam one tooth out of time in both directions and repeat the check. As the cam gets ahead of the crankshaft, there will be a MUCH closer relationship between the valve and the piston- - - -possibly a lockup situation. That kind of test is just "Engine Building 101" to anyone with anything more than "stock" engine assembly experience. I've been building round track race engines since the 1960s.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!