$800 is rediculous for discs on a 44, i just did the whole set up for about $100
you need:
disc backing plates
spindles
stub shafts
hubs
calipers
rotors
you can swap the knuckles if you want, my knuckles have the studs for the backing plate and spindle about 1" off from the chevy donor axle i had, so my calipers sit in a different location, and i had to grind some off the knuckle, but it works