Sorry, im a little confused. MC? You can get 12" caliper mounting brackets right from GM. I believe the bolt right up with your stock hardware. I will double check this and post the P.N. for the brackets if the do. If you want to order the brackets you can through me and get 30% off list.
The rotors are up to you. You could go with the 12" regular GM ones or option for the 12" crossdrilled or slotted KVR's from 3800Performance.com
I bought everything as a kit from 3800. I believe its all bolt on. You can get the brackets from him for $50 a piece. I did check GM for my pricing yet. Might be able to save a few $ there. If anyone is interested I'll call cause I already have them.
If you drill and tap....Make sure its staight...
Fredo, you saw this at my house. Remember.