This is how I wired my 120 amp Denso (I don't have a ballast resistor so "start" and "run" are wired together)

I have a bulkhead on the firewall. The bulkhead receives the power from the battery in the trunk and passes the battery power through the firewall to the starter, ign, etc. The in cab side of the bulkhead supplies power for power seats, etc. I have an external Mopar black regulator on the firewall