As important as the bolt pattern is the back spacing. Typical Stang can't handle more than 4" until you get to 16" wheels and then no more than 4.5, and that will depend on the wheel. Datsun, MGB, 3 series BMW, etc. are good ones to look for. If you stick with wheels made for rear drive cars the fit will be better. I have a set of one piece BBS aluminum wheels the were origional equipment on early 80's BMW's (14x6.5). I have also seen them on 240Z's. I put 195x65 tires on them. Handle very well and the whole set is 4 lbs. per corner lighter than original equipment.
Steve