Just my worthless opinion.....
I have never felt the need for power assist for the brakes on a hot rod
I have had power assist on a couple cars (stock engines however) that had too much assist, and did their best to throw me into the steering wheel
I'd get a non power master, matched to the brakes you have drum-drum, disc-drum, disc-disc, whatever, and then bend my own lines to suit. Just need a bender and a flaring tool.