Going from 4 x 4.5 to 5 x 4.5 should be easy. Measure the diameter of the front rotors. If they are 11", you will only need rotors. If they are smaller, you'll need a kit like this (I just picked this randomly off ebag)
http://cgi.ebay.com/ebaymotors/MUSTA...item1e5edb0335
Does it have a 8" in the rear or a 9"? I would think an 8" if it has 4 lugs. You would probably be better off finding a 9" and having it shortened if need be. Adapters would work for the time being, but you would have to mess with the wheel offset. You can find a 9" from a Lincoln pretty cheap with rear disks if you look. I bought one for $100 complete.