I had manual brakes in my 67 Nova LS swap. Bought a bunch of parts from Tobin at Kore3 so it was kind of designed to work together. They worked really well. My concern is if you do let others drive the car make sure they understand the difference between power and manual. They can both work well, just need to push harder on manual setup. Another thing to consider is maybe adjustable proportioning valve so you can really dial in the rear brakes?