disk swap on '74 or keep drums?

I would do disc on the front. A '74 should have a 4 1/2 inch bolt pattern, though. How does yours have a 4"?

Car with 4 wheel drums got the sbp. That said they also made a lbp 7.25 rear if disc were ordered and you got a slant 6 or 318 (318 could've also gotten the 8.25 if ordered).