You can engine swap these cars just not a 3.8
follow what the grand am guys do and 3.4 swap it.
Then top swap the intake and heads from a newer 3.5.
Add a getrag 282 and your set.
Milzy motorsports
you can swap a 3.8 in these cars me and my buddy are about to do it to his 95 gtp. You just have to use a lumina or monte 3.8 harness and all the mounting holes are there change the right axle out. Do some fuel line modification and a good tune from what I have found its not to bad they say the downpour is a snug fit for headers but some firewall modification or some fancy exhaust making would work.