removing interlock system

I used a 74 interlock engine harness in my 73, fit fine and no it didnt require the interlock device to be in place.

If I were you, I'd unplug the underhood interlock device and then try it without, if it wont run then you'll have to look into the seatbelt wiring. This wont be too hard to figure out if you have a service manual to consult. Good luck.

BTW - The interlock was something that was eliminated after a very short period of being a standard feature. I dont think it survived even one full year in '74, maybe only a few months.