That little Fiero is gonna scream with that blown 6 in it! Are you going to kit out the body? There's loads of exotic body kits for it, interiors too.
I will change the interior with one of Amida F355 kits just because the interior design leaves alot to be desired but I'll not install Ferrari badges, but as far as the body goes It's staying Pontiac. Going to add a hood vent for stability (front end gets very light at highway speeds) and the side vents for functional ram air and an intercooler and upgrade to the HID headlight buckets to improve lighting while keeping the flip up headlights.
When I was growing up a guy down the street from me had one with a V8 in it with a pretty healthy sounding cam and I use to just drool over that every time he drove bye and swore that I would own one some day.
How hard is the swap?
For the 3800 not to bad they're about the same size. I can either make custom motor and trans mounts or buy those already fabbed up. Same with the wiring. It's such a common swap that there are plenty of conversion harnesses and mount kits for this swap. Since the whole cradle drops from the bottom fairly easy once you have the mounts it's almost a direct swap. Gotta custom make an axleshaft from 2 different ones but from what I've researched it shouldn't be very tough. Kind of similar to changing a 6cyl car to a V8 car, mounts and harnesses mostly. Fits quite well.
For the LS engines or most other V8's it's a bit different. Have to have all sorts of custom stuff done. Battery relocation, decklid hinges modified, mounts, narrow harmonic balancer, electric water pumps mounted on firewalls or extended pulleys passing through the wheelwell or in LS applications modified LS4 waterpumps, notches here and there, intakes flipped around (LS's), adapter plates for transmissions. There's kits for them too but they require more and are a bit more expensive. All doable by DIYers but a bit more involved. Carbed SBC's are the easiest of V8 swaps and most common followed by Northstars, LT1's, then LS's. The hardest part used to be FWD transmissions that would hold up, now there's quite a few and adapters on the market for them all from V8archie and quite a few others.
I chose the SC3800 because it's the first one I found cheap of the candidates and is easier/cheaper than most of the V8 installs, and it should provide plenty of power to go quite fast.