Installing a cam for sound is not exactly worth the work or money.
Sound improvements are better gained from replacing the stock H-pipe and/or the catback exhaust.
If you are dead set on replacing the camshaft then you want to think about (other than sound) things like emmissions, future mods(heads, intake???), rockerarm ratios, automatic or manual trans, valvesprings max lift, piston to valve clearence, etc.
Another thing to think about is tuning the ECM (EEC-IV) or not to tune. If you don't want to tune the ECM then that requires a cam that has been designed with consideration for the 94-95 Mustang. These work considering there is nothing else lacking in the engine compartment.
If you are staying with the stock heads/intake most off the shelf cams are going to give you an improvement in both sound and performance.
Edit: check out this sticky for some examples:
http://forums.stangnet.com/665335-94-95-gt-gts-cobra-specific-faq-sheet.html