Took the '72 apart, and found this:
GRRRRRR!
What's more, the other pushrods appear to be a bit loose when not compressed. Opened the front end to double check the timing chain; found a Ford Racing unit installed in there.
Not sure if they wiped out the CompCam that they put in it, put the wrong pushrods in, or if that backfire from yesterday due to the dizzy caused this. I'm hoping it's the latter, for it means the Jethro that rebuilt this motor didn't run it like this (and he claims he did run it). The minimal scrapes on the pushrods seem to suggest recent damage.
At any rate, I'm not going to worry about it now, seeing as I may not be satisfied if I don't pull the heads to inspect. Back to finishing Soylent Green.
-Kurt