If it's an 4.5 bolt pattern(ford), I may be able to help.
I'll check with my friend, he has a pair of 28x10.5's mounted up, he tried on his Mustang. I'll have to see what width rim and backspace. Not sure if they're on an 12" or 10" rim though, the backspace will probably be 6".
I'll check it out and let you know...
John