[njsteve]

You mentioned that the engine and dash harnesses were new, I think?

Remember when I restored the 1972 Trans Am? I bought a brand new wiring harness from M&H Harnesses and it turned out they left out the resistance wire that was supposed to be there for reducing the voltage to the points. Turned out it was punching 13+ volts in to the points at all times, and frying them and the condenser after about five minutes of running. Once they gave me a new harness it worked fine - and they even warrantied the harness two years after I bought it.

Did you buy the engine harness for the 340 with electronic ignition or with points ignition? Could be a similar issue with incompatible wiring. Do you have the part # handy?

IIRC, the Cuda uses the firewall-mounted ballast resistor to do the same thing. I always carried a half dozen around in my glove box because they would go bad - either totally fried or heat related partial failures. You may have to go with a baker's dozen of them.