Most drag race calipers use 1.75" bores. Use number of bores in the system to determine piston area. Basic rule is 1-1/32" MC for 2 piston front/4 piston rear system. 1-1/8" MC for 4 piston front and rear.

Using anything else, you have to do the math. Total area = πr2 x number of pistons

Pedal ratios make a difference too.

Some of these kits use calipers with small (1-3/8") bores. I got caught (once) trying to figure out why the brakes wouldn't work on a car that had Wilwoods with these goofy bore sizes.

Plumb the brakes into the correct port on the MC, according to your configuration.

Spend some money, ditch the torn up rubber ring, and put one of these on the car. If I had a dollar for every car I've seen torn up...