Hi read Your post. Have like car similar to yours The brain child I bought it from put 12v battery in it - ground. Had generator converted to 12v with regulator. Ans a bunch of other stuff. Drove it home 150 miles with the 12v system trans trans shifted ok. Had car for three years. took out yesterday no automatic shift to 2nd or fourth. Checking voltages at circuit breaker and resistor block mounted by coil. so far that's looks good. Will continue to check trans,soleniod,govener and interrupter switch. All in all put a ballast resistor from your 12v ignition lead to coil. The 12v going to burn out the points. All 12v cars with points have that ballast resistor. If you want I can keep you posted about trans diagnoses