First is your steering a front or rear steer design?
Then I'd go for a walk through the local junk yards and look at front ends from 70's and 80's rear wheel drive GM's and see what looks similar to what you have.
Gm has been pretty good at keeping the same balljoint pin taper for a long time,so you should be able to use your stock upper and lower comtrol arms and tierods and just install the newer spindles and brakes.
You may have to shorten/lengthen the tierods a bit to get the correct toein and then have the frontend aligned.
Also get the combination valve and master cylinder to match the disc brakes to make them work correctly.
I've done this before on a 55 chevy and on a 57 ford cause at that time I couldn't find anyone that made a kit.
I hope this helps