Quite frankly, the easiest thing to do is buy a 63-66 C10. The vast majority of aftermarket stuff is for C10's. CPP has an 8 lug disc brake kit. It's $200 more than if you had a C10. Even if you go this route, you still have wheel/tire issues to figure out (unless you're happy with your current). You're stuck with a limited selection compared to 6 or 5 lug wheels where you can run a myriad of 15" combinations.
CPP The other thing you can do is find a junker 63-72 C10, pound the rivets out and bolt the front end into yours. Everything easily upgradable from there. Then swap the rear out to match. This also gives you the option of changing the gearing in the rear if you wish to do so for better driveability. You cannot change the gearing in your huge C20 Eaton rear even if you wanted to because nobody makes different gearing for that nowadays. Some of the 67-72 C20's had a 4.11 rear though and that could be an option if you wanted to keep it 8 lug.
