[Dave1695]

I used to work for an aftermarket brake manufacturer as their tech adviser. With MC on firewall, you do not need residual pressure valves, they are only used when the MC is mounted lower than caliper/ wheel cylinders ( as on a Hot Rod) to avoid fluid drain back to MC. A 1 1/8 inch bore is for power assist brakes, use an aluminum Corvette style MC with one inch bore, and an adjustable proportioning valve in the line to rear drums. It will allow you to regulate pressure to the drums and avoid rear brake lock up. Just my two cents.