Not to drag this up, sounds like a few got mighty upset...but as a former autobody tech...speaking from experiance...I chopped a pickup I had, made it a hardtop convertable...alot of people was like you spent $$$ to fix the a/c then I chopped the roof.
My theory is it could be done, but probably the best route to go about this is finding a 5.0 fox mustang shell, cutting away the upper body, just leaving the floor, rockers, and front clip.
I would work on trying to do a decent setback on the engine/trans...The dash assembly on these cars are pretty deep...you could take out a portion of the fire wall, ditch the factory HVAC, and maybe just adapt a heater box from something else.
Welding would be a major issue...having someone knowing what they are able to do is pretty high up their...you'd want someone with a good 220v welder, a 110v unit ain't going to cut it if you have alot of heavy welding.
As far as the steering, etc, if you ended up using the front clip off a fox mustang, all your suspension and steering issues are handled.
swapping out the rear floor pans off the mustang gives you everything you need to mount up the 8.8 rear axle, and a place for a factory fuel tank, or a fuel cell.
I don't know what the track widths are, but I can't imagine there being a huge difference.
As far as making a heavy car run, I have a 4,300 pount Torino, call me crazy but heavy cars can and do run quick 1/4 mile times.
Worry about the ounces, and the pounds will fall.
my 2 cents. It just depends on you.
