I gotta ask: why was this alternator on your engine in the first place, and why do you want to keep it instead of a Ford product?
I've swapped the guts of one alternator for another plenty of times but can't say I've gone from a single wire to a 3G. Usually it's to replace the guts of a burnt out unit in a chrome case with stuff from a reman from the parts store to keep things pretty. It's simply a question of space and in some cases the ability to secure the innards.
I'd ask why not stick with the single wire GM unit? It's simple, cleans up the other crap no longer needed underhood and is readily available. You can get one to put out stupid amounts of energy to power damn near whatever you might put in the car too. It's not like Ford makes their own alternators so you're being brand loyal. Give me something I can find on the shelf at damn near EVERY parts store in the country, please.
Why do you need such a high output alternator in the first place? What's so special about the way the old alternator mounted that you couldn't simply buy/find brackets to allow mounting of the "special" new alternator? It seems you are throwing more and more money after something that doesn't need to be so difficult.