I recently finished converting an 80s Raleigh Pursuit to a single speed and the last part I need to ride are a set of brakes. I like to coast! I have no idea what kind/type/size brakes to buy. Does anyone know what will fit my bike or any suggestions for what brand I should buy? Thanks everyone! I can't wait to ride.

Measure the distance from the center of where the brake mounts to your rim. If the bike originally took 27" wheels, it'll most likely fit with a tektro "medium" reach caliper 45-55mm.

It measured 55 mm, so I might have to check those out. I bought a random pair of cheap campagnolos off eBay and the bolts to secure the brakes to the frame don't even make it to the other end

You probably need to drill out the fork to accept modern recessed bolt type modern brakes. 8mm drill bit. Should take 10seconds to drill out the back of it. Most modern "short reach" dual pivot brakes will not reach 55mm.

For a single speed, you need the type that has one front, and one rear.

Like Op said, drilling out is easy, but the reach may not be enough. Get some older bolt on types, they'll usually fit. Otherwise somewhere like YellowJersey might be good. They have a range of brakes with differing reaches. Or, now you know the reach, get back to eBay and ask the sellers for measurements before buying.

Is this what the type of brakes I need are called? Pivot brakes?