If you’re young and strong and don’t have lower back problems, there’s nothing wrong with manual disc brakes. They don’t require much more pedal pressure than manual drum brakes. The drum brakes are self-energizing, while disc brakes are not, so the discs take a little more pressure.
You’ll probably want a rebuilt master cylinder, but one from the wrecking yard might be rebuildable or useful for a core charge. You will also need to split the lines front/rear and add a proportioning valve.
I’ve had very good service buying almost all my aftermarket parts from Classicparts (formerly Chevy Duty). I bought my door seals from them back in 1998 and they still look like new.
http://www.classicparts.com/
If you do a search for “gas tank” you’ll find there are dozens of threads and options available.