15/16" bore might give too much pedal movement and maybe bottom out before max. pressure is reached. Maybe try a 1" bore MC first if you can borrow one somewhere.

You don't need a prop.valve with 4 discs, provided the rear discs/calipers are sized smaller then the fronts. But an adj. pressure valve will help dialing in the brake bias.
But since this is a dragracer, imo you want a little rear brake pressure-bias to the rear slick tires as the frontrunner-tires can only take so much braking force before they start skidding.