Dear Matt;
You may have installed the distributor wrong or it had a bent shaft as Chuck sugests, but you would have probably noticed that early on as it would have wiggeled around & been noisy. It probably didn't 'freze-up' as it would have spun in the block.
I would check with Larry (novaman/twisted 6)on the interchange issue, as he would know.
Bruce is right too, but you didn't mention a 'high volume' oil pump.
All that being said; I would bet that the cam had a bent or chipped tooth (now broken) from the onset that no one saw. Once running, it was just a matter of time before "self destruct".
If your running a stock oil pump & cam (next one) then a stock gear will be fine on the distributor. You might run your dist. on a Sun machine & make sure It's okay "just for drill".
What happened is really rare.
Good luck, John M.......
