Here is what I got from a guy I work with who did it on his 2002 (or so) GT:
I had the momo I think its the monte carlo wheel from one of my volkswagens. I bought an adapter from some company I think it works on 79 up mustangs. Maximum motorsports website has the same steering wheel and adapter I used. I also used a 2 inch OMP spacer to bring the wheel closer to me. I had to remove the clockspring mechanism behind the steering wheel, and the horn doesnt work unless I rig up a switch. I had some trim plastic and made a panel that goes where the clockspring/wire mechanism was or else you see all the steering column stuff.
Going with an aftermarket wheel means no airbags, however the FR500 allows you to keep the airbag...