Dual master for 4 wheel drums, use a 1 inch master, a 10 pound (red) inline residual valve for each line (wilwood). You can use a distribution block if you want to wire in a brake warning light. No combination valve needed although some use them anyhow. You don’t usually need the proportioning portion of the combo valve.
https://www.camarocentral.com/1967_1969_Master_Cylinder_for_Manual_Drum_Brakes_p/brc-145.htmhttps://www.camarocentral.com/1967_1969_Camaro_Brake_Splitter_Distribution_Block_p/brc-107k.htmhttps://www.wilwood.com/Search/PartNoSearch?q=residual%20pressure%20valveFor a disc drum system, use a 1 1/8 bore master, a 10 pound inline residual valve (red) for the rear brakes. Because the master will likely be lower than the front calipers, or pretty close to that, install a 2 pound (blue) residual valve. Use a combination valve with this set up.
https://www.camarocentral.com/1967_1969_OE_Style_Master_Cylinder_for_Disc_Brakes_p/brc-147.htmhttps://www.camarocentral.com/1967_1969_Proportioning_Valve_p/brc-235.htm3/16 lines are fine. Front port of master is for front brakes, rear port for rear. Some combo valves have two ports for front brakes, one port for each side. You can run two lines if you choose, or plug one port and run one line similar to stock.
