Then LS it is. Anything stock looking, 2bbl and crappy factory exhaust mean no performance, don't bother if that is the criteria. So no 4bbl and intake off a factory 4.1 V6 RWD? I believe they were 81 to 85, CCC and EGR. Your factory ECM should run it no problem. I would start with a 2004R and upgrade the gears to 3.42 plus.
Realistically it's not worth the effort.
When the engines were new the difference between a 3.8 and 4.1 was negligable.
3.8 - 110hp, 190 ft lb
4.1 - 125hp, 205 ft lb
It wasn't a case of shorting the ratings for isurance companies either, just never was a firebreather.
You've also got to account for the fact that the 4.1 gained some of that additional power from the extra 21 ci displacement.
Neither on the street nor on the butt dyno will you see anything appreciable or particularly noticeable from the intake/carb but will see a lot of work doing it.
A maintained 3.8 runs forever. I like the motors for what they are. However, it wont get you there very fast. The fast 231 were the
grand national motors that shared little but the block and sometimes head castings with the naturally aspirated ones.