Almost ready to go shopping need help please!

[xfsketch]

Application 1972 Chevy C10 1/2 ton LWB pickup Custom Deluxe with standard stance and a 305 Monte Carlo motor that has a mild sized cam and a 759 cfm Edelbrock 4bbl carb ( soon to be a smaller carb. I have a. 2bbl Holley I'm thinking of putting on it?). 3 spd on the floor tranny, disc up front drum in rear

First off sorry for all the questions. The wheel design I like most for my truck is the Boss 304. I want to run 22" in the rear do a disc brake conversion. A kit is available at Summit racing for. 474 bux! Not too bad of a price I guess. The problem is the only 22" Boss 304s available are 5x4.75 bolt pattern. I heard I could do a disc brake conversion for cheaper by hitting up the junk yard for a certain ford truck and they bolt right on?

My questions are as follows:
1. Is there a disc brake kit with 5x4.75 bolt pattern for our trucks?
2. What are my options to run these wheels on the rear? I mean a conversion kit wouldnt work right because it would add an inch or so to the spacing?
3. Couldnt I just purchase different rotors with the 5x4.75 bolt circle? It would be a waste to buy an entire disc brake conversion kit then right, so is there a cheaper option I can go with at Summit to piece together a conversion with the right size bolt circle?

Id really like to deal all with Summit because I have one nearby. So far my list consists of the following:

Disc brake conversion kit
(2) 22x9.5 Boss 304 w/5.810 bs and 5x4.75 bolt circle
(2) 265/35r22 Yokohoma tires
(2) 20x8.5 Boss 304 w/ 5.25 bs and 5x5 bolt circle
(2) 255/40r20 Yokohoma tires
(10) conical seat 60 degree Cragar lug nuts (what size the wheels call for)