I use ford rotors off of an explorer front, gm small metric calipers (monte carlo, 83) and weld on gm caliper mounts, im happy with it, done it to a few of my vehicles, along with customers, they get new stuff, ill use junkyard parts, lol.
Gotta shave a bit off the weld on mounts. The axle is bigger diameter than what a ford nine inch is. I clamp the bracket to the rotor with a one inch square tube to space it away. Just have to have the caliper bolts screwed in and just the width of a washer away from the rotors edge. You get it to close, the rotor will rub.
I hate drums, so i do this swap all the time, basically the same thing every circle track car has.