Hi Dino. There are numerious magazine articles on brake conversions. Check back issues of Custom Classic Trucks and Classic Trucks. You didn't say if you have a 2 wheel or 4 wheel drive. You have two routes. Do it yourself with a doner 70's, pulling all the parts, spindles, tie rod ends etc. OR, there are numerious suppliers of kits for a power & non powered disk brakes. Master Power, Early Classic etc.
Do your homework ! Research what is available against what you want to achieve and how much you want to spend. Personally, I think when it comes to braking and steering, don't cut any corners, this is money well spent and involves your life.
I completed a power steering, power disk brake conversion on my 64 over the winter. The braking is un-by-god-believable and you can't believe how easy it is to steer even with Goodyear GT II's all around.
Good luck & Regards Dennis