I need advice with 69 c10 Truck And site

[Spalma916]

Hey guys,
My name is Steven and I own a 1969 chevy C-10. I’ve taken it completely apart; sandblasted frame and used the KBS rust, primer, & paint system. Now I’m ready to put this together and realize I know very little about rear ends an differentials etc.... the rear end I have has 12 bolts on the diff. Case. It also has drum brakes that I’d like to swap out for disc brakes. I guess what I need to know right now is if there is disc brake conversion kit I can get and is a 12 bolt Differential a good one or should I look for something better.
My main goal for this truck is to keep the look as original as possible with adding the state of the art upgrades of today such as disc brakes all around and the gas tank in the back.
Please let me know if and where I should get the disc brake kit, the paint is drying on the frame and I’d like to get to work putting it together, thanks