<VV> Engine overheat problem update

[Kinzelman, Andy]

Guys,
I posted last week about my friends car overheating, then refusing to run afterwards.  Since the last post I removed the exhaust system (no help), and he swapped the carbs onto another running engine & it ran fine.
We swapped in another 110 distributor onto the engine & it now runs good (so far).  Of course, it may drop a valve seat sometime, but for now it seems fine.
Is there any way to confirm there is a valve seat problem without removing the heads, or running the engine until it craps out?  The compression was good on all cylinders.
Thanks,
Andy