Like your style
Hey man, what you want to do is admirable. Like you said, your not concerned about resale value, your keeping the car which is totally cool.
As far as the technical aspects of doing this, the guys are not trying to keep you down as far as your ideas went. Its just that it would cost a fortune to do what you want to do and do it right.
You would have a hell of a lot of money in a car that would not be reliable, would never handle like a GT, run like a GT, or give you the pure satisfaction of a GT. Because its a poser, and allways will be.
And I know money is hard to come by, but no kidding you would be money ahead to trade that six banger for a new GT and be done with it! I wouldnt waste 2 cents on turbo charging your six cylinder Stang. You obviously want V-8 power, go get it man.

imp