I am thinking of going to a non power dual master to replace the single on the HJ. What brand of MC have you used and what is needed to plumb into the lines to make all work?(unless I find a firewall pedal ass'y off an other car and do the switch). I did the switch to dual on my 57 but that was on the firewall. Thanks.
First off are you going to run disc or drums? 69 Chevelle is available in either style and easy to come by. Since the master will be lower than the calipers or wheel cylinders be sure to run residual pressure valves in the front and rear lines, otherwise you'll never keep a hard pedal with normal travel.
on my rat truck im using a chev truck master, you have to use a large bore if you are not running power brakes. if you are running an all disk setup use the 2lb residual valves to keep the fluid at the calipers if the master is lower than them.