I have wired up a few 3rd gen conversions , I never use the computer to start the car , the 1970 system is far cheaper to maintain & more reliable , a simple start relay on the inner fender connected to the start solinoid .
I had a 210 Town & Country van , 6 out of 10 times it started just fine but 4 out of ten the key would signal the computer to start & it refused , no way will I trust a computer to start the engine again when the tried & true system used for 70 years works