RC Motorsports has a mustang II front end conversion kit. It runs $2,000-$2,500 but you get the disk brakes and you also remove the shock towers which some people think is a good thing, others think it is a bad thing. There was a post about Fatman Fabricators showing off one that there either selling now or planning to sell that uses late model mustang parts. 6 months or so ago i remember somebody posting a do it yourself one but there was some sort of issue with turn radius.
One other option i remember is a tight ratio stock gearbox. Its not exactly the same thing but the effect is close.