Wow good luck to your dad and his business. Truck looks great, and hopefully you figured out the ICS problem. Found that City Racer actually sells the one wire and two wire ICS. When I rebuilt my head in 2015 I went with a CCOT ICS as mine was dead (see my build thread). Well I have had a high idle (not sure if that is due to the ICS) and backfire issue on decel at about 2k rpm (which I believe one of the threads says is when the ICS kicks over to the carb vacuum). Anyways, I have a spare carb that
@HemiAlex lent me and will swap that on to see if I have the same issue. If not, then I will be getting one of City Racers.