4 to 5 hey, i also have converted my car to a 5.0 but i won't need 5 lugs until i put alot more horse power in my maverick. now i do have 5 log discbrakes to put on it and a 9 inch so all that said. no i don't think you'll ''need'' 5 lugs just yet.
I knocked the hubs out of some 4 lug drums and installed a 5 lug hub. 1 of the stud holes will line up so I put a bolt & nut in it and tightened it down. Marked and carefully drilled the drums to 5 lug. Worked out fine. Granted I had smaller frt drums and a bit larger in the rear (5 bolt 8" rear end) but it worked fine with the 200 6 cylinder. I wouldn't recommend for a V8 powered car. I heard about this from a guy that did it to a 4 bolt Mustang.
There was also a 7.5" rear that was put in the early 70 Mavericks and it was junk hence the reason it was only in there for a partial year
to change the rear to 5 lug you will need to get a 5 lug rear. the axles, housing and brakes are all unique to the 4 lug rears. ford used 7.25 rear that gets mistaken for a 7.5.