11 3/4 brakes

I was just given the caliper adapter and calipers from a B250 van. The adapter is heavy duty (FAT) but the bolt holes seem to be the same as the C bodies, 3 3/4 center to center. The caliper takes a larger pad, about 25% bigger and the piston measures 3" across. I have the Kframe ready to go in so my question is will this work? I have 74 disks on the car now and want to move up to 11 3/4 disks. All I need to do is get the rotors for a C body, 1976 Dodge Monaco is what I'm planning on. If this works it will put a lot of pad on that rotor!