One other problem that can occur from having your distributor too far in the hole is pressure on your oil pump. The oil pump will break if the distributor is bottomed on the pump.

Had the same problem on a gen6 502 with crane roller cams with the cast dist. gears. My prob was it would wear out 2 or 3 teeth on the dist gear(cast MSD gears). I never let it fail and the other motor never had an issue.

Turned out to be the cam, I couldnt see the cam gear in the engine, but after pulling it out it did have a wear issue on the cam gear. New cam and dist gear, both looked new after 80hrs.

LE