Tuning with jets, Power valves and an O2 guage

A guy on Moparts mentioned a buddy had a similar problem with a 496. He was using the same Fel-Pro head gaskets that I have and the Fire-Ring that surrounds the bores had burned! The guy apparantly found that the fire ring was slighly smaller than the size of the combustion chamber and had melted at least one ring.
I just went out and laid a Fel Pro 1009 on a the deck of a .030 over 440 short block. I can see that once the gasket is compressed, this is possible. I don't know exactly how this could translate into detonation, but for that guy, his fix was to use a gasket with a bigger bore diameter.

http://www.summitracing.com/parts/edl-7325

This one has almost the same compressed thickness, but a bigger bore size. I don't know how a burned "fire-ring" translates to detonation except that it is a hot spot igniting in the chamber? How do you know if it is an issue without a teardown? I'm not against pulling the heads, I'm just getting tired of chasing dead ends!