71 mustang brakes

i wanted to know that if i used a set of brakes from a granda with the 4 lug if i could get a 5 lug rotor and put it on the brakes. would it fit? i know 71 came with a option of disk brakes so i was planning on useing the 5 lug rotor it could have came with on the 4 lug set from the granda. are they different sizes or the same but with one more lug?