chatcher,
sorry, I assumed you had the mark vii rears.
Tony,
If you want to go cheap as possible, go to
http://www.stangparts.com/ and read their how to article on 5-lug swaps. Sorry, I assumed you were wanting a drum to disc swap also. To go with the Mark VII front rotors you will need the 87-93 spindles $30 and calipers $20 per side respectively. I'd try your local salvage yards to get them. If you don't have any luck locally, I have them. Let me know and we can work something out.
Good luck,
Rob.