Rotors are 11" and 1" thick but it's only 3" and some change on the hub mounting surface to back of the rotor. I also can't find any stampings on the calipers so these very well may be oem brakes.Can you tell me if these are about 11" diameter, 1" thick for the rotor and about 4" from the wheel mounting face to the back of the rotor? That'd mean they were probably OEM.
Besides that I'd give REAL serious consideration to going to 1/2" wheel studs especially with aftermarket wheels. I used Dorman PN 610-395 which is $9/10 from Rockauto for the Lemans. Odds are good they'd do you right too but check to be sure. I don't trust 7/16 studs on newer wheels with larger holes after what happened to me in the Lemans. If I wasn't trying to move and had the lathe up I'd offer to cut up your rotors for you. It's likely if you looked through my build thread the majority of what I did would work for you as well. The abutements are different for C5 Calipers but supposedly other than that you just slap on the 13" rotors, calipers and abutements and they'll work with those adapters too.