[colgad]

I have done this job two ways. First i rebuilt the system using replacement parts but converting to a split system.
Excuse me but having a single system is just NOT the way to go. I have been in a Truck that lost a cylinder and then having no brakes at all is not fun coming up to a busy intersection. If your restoring a museum piece then yes keep a single system but if your going to use your truck and keep it, why put your life and others at risk. Its a simple conversion to a split brake system.
Once done you still have drum brakes and widow maker rims.

The second C50 I did I went with all disk brakes. I know not cheap but SO SO SO much better and the parts are available everywhere. The easy part is to just swap out your rear end. This is pretty easy and really not that expensive. You get modern 10 lug 22.5" rims so you can run modern tires, gone are the 20" widow makers. The front is harder but do able. Find a GM P30 bread truck that has a straight axle and you can use the spindles with a small mod. This will give you disk brakes and 8 lugs than you can use adapters to go to 22.5. 4 wheel disk brakes on your C50! I used 2001 Chevy 3500 booster and a 1992 Topkick master cylinder. Small firewall mod but worked great.

I swapped my front axle for a freightliners it was too wide so I cut 10"s out of the center and welded it back together. Not for everyone but worked for me.