When running a disc/drum setup, you want to use a 2lb residual valve for the front and a 10lb for the rear. You also want to run them inline as close to the MC as you can. The proportioning valve should be on the frame at the back so it's accessible from underneath to adjust.
The residual valves keeps brake fluid from draining back to the MC. That way the pedal does not get mushy. The proportioning valve will help you regulate pressure from front the rear.