Bent and Broken Push Rod 350 SBC

[LongBox]

69 GMC 910. 350 4bbl SBC, TH 350. Truck sat for 14 years, with apparently an occasional start. Truck was garaged all that time. Gasoline smelled pretty bad. Truck started, after some work on the ignition, and actually ran real good.

My plan was to use the old gas up, then fill with new, and do a tune up to get the dwell and timing correct. Started to run rough, then began to clatter.

Compression tested around 175, cold, throttle not blocked open, except for two cylinders. One was at 135, the other at 0!

Pulled the rocker covers, and found one pushrod not engaging the rocker arm at all, and one pushrod broken off and bent as well. See picture, which I hope shows up below.

Question, before I get into this any further, is what might have caused this? I'm wondering if the old gas varnished up the valve stems and guides? Or maybe ghe fact that it was not timed correctly (spark) did something? It was spark knocking under load...

New pushrod in photo for comparison.