My 53 3100 had 1/4 to the fronts and a single 3/16 tot the rear that split at the rear axle before going to the brake cylinders. Now I'm installing my disk conversion kit and the proportioning valve is set up to replubm exactly that way.

The 1/4 line is going to give you better brake feel and modulation as it will allow the pedalmto move farther through it's stroke as the caliper demands mor fluid as you increase pressure. A larger diameter line moves allows more fluid to flow with less pedal travel. This could cause the pedalnto feel like it is hardly moving through its stroke before maximum braking occurs.

1953 Chevy 1/2-Ton 3100 5-Window
1937 Chevy 1/2-Ton
1970 Chevelle