Had the single point part vacuum, part mechanical advance (guess Plymouth had their dual point optional). So before electronic ignition, dual point was the only way to go along with what looked like anyways a coil that put out a higher voltage than stock. Now I always had trouble with misfire unless points and condenser were in perfect shape. I believe the single point would actually chatter and float per se. I had a similar Ford dual point distributor that fit and worked perfectly, problem solved...... Bought an ACCEL dual point, mechanical advance only distributor. Both point sets could be set with engine running using dwell meter (what’s that lol?). Think I set the advance with the 15 degree weight advance as I recall (bunch of selections with Allen screw) was the best selection. No exaggeration, I thought that car had a second carb. under the hood. I couldn’t believe the unleashed power; by then we were down to 280NHP on the 383CID. Not the same as if going to electronic ignition at all. Dual point will not skip, points overlapped for greater spark buildup, super quick timing advance with just mechanical weights. No timing advance needed there for any improvements. And the down side...... my word, where’s the gas going to. A few passes and tank would drop by 1/4. Could get 16MPG with stock distributor and along came the gas wars! Similar to photo but those weren’t geared for road runners, had a tab and slot.