Master Cylinder

Since I just converted my 66 Barracuda from 9” drums all four corners to the 73-76 bbp 10” disks and 10x2-1/2” rears- the brake master cylinder for that has the larger chamber up front for more volume. When you step of the pedal the internal piston is larger to accommodate the caliper volume. Vs. the rear wheel cylinders are 60% smaller more fluid would bottom out the pedal on a single line system.

I’m my opinion I would say “yes” you will have an issue with a dual in equal system until you actually have the components on there with the needed ratios to match the resivoir.