The brackets to mount the alternator, and the alternator are easy to come by. The offsets are different on the pulleys, so you would want to change to the steel water pump and crank pullies. Voltage regulator is different. Charging harness is different. Since most of the time the harness is not that great, just replace with the alternator harness. The underdash stuff requires a little work, Mustang Monthly had a how to on this years ago, will try and find.
Several years ago, had a D code 64.5 cv. Wish I'd kept it, but anyway: always wondered if it would have been possible to fabricate an alternator using the original generator housing, thereby keeping the original look. Wishful thinking???? ::
A option is a ONE WIRE alternator. They are GM that have a conversion done to them that all you have to do is put one heavy guage wire to the battery. Of course it will not look Ford and the brackets and pulleys will have to be reconfigured. It has been discussed here so do a search for ONE WIRE ALTERNATOR if you are interested. John