I have done a few different old straight axle conversions just using what I could find and a little ingenuity. Find a rotor from some tuck of similar size and do some measuring on the distance between the inner and outer bearing.. Most bearing places can come up bearings if given the inner and outer dimensions. Even better if your drum separates from the hub, then you may find a rotor to fit your existing hub. Once you have rotors, choose a suitable caliper and build the brackets.
this isn't the best picture but It's one of my "conversions". Axle was Econoline, rotors from a Ford Aerostar, homemade brackets and Chevy metric rotors. I could have used Crown Vic rotors but couldn't fit the 14 inch wheels I wanted to run. You get the idea.