BTW, you may want to call Grant and ask him if he thinks is ok to run a rag disc with a marcel. Every time I tried it, the marcel would allow the disc materiel to flex and over a relatively short period of time, the disc materiel would fracture and fall off. That cost me 500 bucks one night, and I had to drive home without a clutch. Also happened one night at Alcoa in a buddies car, but luckily, I didn't have any cash out that night.
They used to make those discs without a marcel. It's at least worth asking about.