Walk out and Look at the Car.... Do you really really want to try this ???
It will cost more than the cars worth 3 times over... 4500 with glass and welding, fiberglass work, and moving the A pillars back and in... It is short enough the way it is... Put more into the motor like a SuperCharged 3800... And make the body under side stronger... Then split apart to easy... kind of like making frame rails for it....
Good Luck....
Best Fiero cut down I've ever seen was the roof removal and 2" inch to 8" center w/s Kind of like Porsche Spyder or speedster... Yes had to make frame under the body to keep it in one piece...