Yeah,the 3x00 hybrid,L26/L67,4.9 and 4.6 N* are all good swap engines.
The 4.9 is extremely easy to install I understand,with the L67 being a close second.
Only issue with the 4.9 and N* swaps are the programming.
One guy has finally disassembled the stock programming enough that he can swap in segments from other PCM's.
He can't program them completely yet from what I understand but he has found a way to get the STS timing and stuff in there.
I'm putting a 3400 topend on my 3.1 turbo mcclaren engine with a T3 style turbo.
Mine should be almost straight forward swap with some adjustment's for axles and the 440t4/4t60 trans mount I think.
Still stripping the TGP so not sure how it will go yet.
Your uncle sounds like a fiero owner for sure.
I've had mine for about 4 months,and love it.
It's the funnest car i've owned,and i've owned some fairly nice cars.
I now own 2 other's besides my driver.
You can't own just one fiero,not possible.
Gotta have at least one for parts since so many parts are one-off.
