Doug, over time I replaced the entire stock Pantera braking system and plumbing. It all started with the ridiculously small, heavy rear calipers & limited front brakes. A few years after we bought it in 1980 I added ATE's Porsche 911-S aluminum 2-piston front calipers to the rear along with what Wilwood called their 'cable operated spot brakes'-popular on go-karts, for legal e-brakes on custom brackets. My rotors are early Porsche ventilated. To balance the altered system, I removed the stock prop valve and added a Corvette/Kelsey-Hays adjustable prop valve in the rear plumbing, adjusted to lock the fronts first. Still works great.
On one trip to 'Vegas, Judy suddenly lost both front brakes in the stock master cylinder to wear. Except for a long travel brake pedal, the car drove normally in town & on the highway, using only the ATE rears. After we got home (550 miles!) due to cost at the time, I fixed it with Don Byers' GM power brake adaption. I removed the 'keep-alive' ball-check valve in GM's master cylinder for less pad drag. That master cylinder is dual bore size, neither one being exactly the same as OEM. GM's dual stage vacuum diaphragm is larger as well as being lighter overall. At that same time, I replaced the front Girling calipers with Wilwood Superlite lls that were 1/2 the weight with equivalent stopping power.
I also added dash-3 Aeroquip hoses & aluminum fittings for the entire car including the clutch. On gauges, I see 1150psi in the front brakes & around 1000psi rear in panic stops. All this actually fits together; I run 245-50 x 15" BFG Euro T/A front tires & 295-50 x 15" Pirelli P-7Rs, both V-rated, on 8" & 10" x 15" Campys, with Porterfield R4-S pads all around. Sadly, some of this stuff is no longer commercially available.