I think the SBC version I have collecting dust somewhere uses a Mopar cap & rotor. I may be mistaken though.
lemme see if this is right too.. i had one almost exactly like it on a 460 in a jet boat. i did some research and found the top was modeled after an AMC 360 distributor. so being a cheap ******* not wanting to pay ungodly amounts for an accell unit i got a $5 one from autozone for a 80 wagoneer and it worked great.. course that was for the ford distributor but ya never know.
My BEI takes a standard MOPAR cap. I didn't look at the GM version that close. They were owned by Echlin and your cheapest way out and best quality was and is Echlin parts for them. We used to use Echlin parts in all the Accel stuff when I was a kid. The only thing that anyone that I knew that was Accell was the stuff that showed.