What size brakes did you order ? When I put my front end together it had what was called the big brake kit which turned out still wasn't big enough.
You need nothing smaller than 11 inch rotors and big GM calipers like what came on a 69/72 Chevelle. My first " Big Brake Kit" was what is called metric brakes from a third generation Camaro , 10 1/2 inch rotors with a little smaller caliper. There is a BIG difference between the two.