This Cobra Is Killing Me

I have had my Cobra for 20 years now. It has been a love hate relationship. Right now it is hate. The engine is 390 out of a old 1962 Patrol car it was a original a 401 HP motor. The original overhaul was in 1987 it lasted till 2000. I overhauled it because it had broken two piston rings and since the overhaul it has used 22 quarts of oil in 2500 miles with no smoking and the plugs are clean. So we took the motor apart to see what we could find and everything was good. So I replace everything again and the new Comp cam I installed broke Comp sent me another cam and then the new Cam and the front sprocket and double roller timing chain broke again. Ok now I got that fixed and the number eight push rod bent, but all the valve guides and rockers are all good, but this is the second time this has happened on the same push rod number eight. This engine has been balanced MF and I have checked and mic anything I could think of. Any ideas or help would be great. I have overhauled at least fifty engines in my life and have never had any problems till now.