2 Bent Pushrods in 350 SBC

[GregWeld]

An adjustable push rod is a checking/measuring tool.... there is no such thing that you could use to actually run the motor with.

At this point there is only ONE correct way to fix/diagnose your issue.

Drain your coolant
Pull the distributor
Remove the intake
Remove the head and fix the valve

There's something going on here that needs to be solved. My guess is you have a cam going flat.. which you'd be able to see if you remove the intake manifold. That would explain your running rough and inability to keep the car in a steady state of tune. The cam "going away" would allow the lash to open - pounding the pushrod - and stressing the valve train.