I dont see what differance it would make to use the break calipers from a B body. I just completed the conversion on my 86' GN using the parts from a 1999 camaro only thing I had to manufacture was the mounting bracket. Theres a post within the last 45 days that has pictures showing the conversion, manufacturing the bracket was not too bad. I was able to download the picture of the bracket and took the angles on the picture and dimension and put it into our autocat system and it gave me an exact blue print of the bracket which made it alot easier to cut. The whole conversion does take some work and machining, you have to remove the spindels and you will need to cut the rotors and spindels, as you'll see in the post. But the differance using the 99' camaro breaks set-up is excellant and well worth it, the car is more controllable and stops on a dime. The price to do the conversion was not too bad right around 2-3 hundred dollars depending on where you get your parts.
Ralph
