65 Barracuda daily driver

Yeah, I knew you'd have to take the down pipe loose again. I'd try the bolt first with the adapter still in place with the old gaskets, to do a test fit with the down pipe to see how it goes. Save the new gaskets for the final installation. If it were me, I think I would heat and ding the down pipe if needed, to get good clearance on the bolt head vs cutting the bolt head. That bolt is worth what the dude is asking for the kit!