I have some brake issues also. I have a master from a mid 90's Ram truck 2wd and it is for power brakes and I have manual stock rear drum and stock front discs off a diplomat and just ran the lines with no prop valve and I seem to have a very hard pedal. Basically takes bolth feet to stop it but they seem to work good other then the hard pedal. I was thinking it might be the rod angle to the master. It is going uphill just a little. Anyone have any ideas?