The black / yellow stripe wire is going to the positive connection on the coil on both cars to run best.

hi,just a reminder to check if you have correct balancer and the correct timing cover. I think they moved timing marker to opposite side after 68 model year? not sure exactly but worth checking out.

The timing mark is on the driver's side. The timing cover and balancer are original 72 340 parts that came off this car and engine to the best of my knowledge and memory. The timing mark lined up when I re-stabbed the distributor drive and distributor. And the rotor pointed reasonably well where it should. My 1972 Plymouth shop manual shows a picture of the timing mark on the driver's side of the timing cover.

Have you physically checked to make sure the distributor has the proper mechanical rotation inside ? The shaft would be the same for either rotation , if it has the wrong reluctor cam it could move the timing in the wrong direction.

But if you have 33 degrees initial you should have a locked out distributor ???

I don't know that I have watched rotation with the engine turning over. But I have figured out how to tell if the distributor is correct for a small block or big block. I have also tried a second distributor. Swapping the coil wires made the engine run better while the weird timing light readings continued. Now I'm more thinking I'm not getting noise free pickup. I have Spiral Core wires and the wires are a little close together. I haven't really started those checks yet : moving wires around, moving the pickup around, clamping on another plug wire. Maybe even trying some RF shielding of some sort. My symptoms include a strange move back to the initial timing, which may indicate a reset of the timing gun. This idea came from another site where a guy was warning of interference from racing wires or other non - stock wires.