Ultra conversion?

I love my 97 Ultra with 209,000 miles on it now. (Got it with 90K) Tranny is starting to act up and will be needing to have it rebuilt if I'm going to keep the car. Investing 2000.00 and my labor might not be a good investment for me. Checking all over the internet/local I could replace the tranny with used but because of being the 4t65e-hd it is a hit and miss situation. My question to everyone is can a complete3.8l/4t65e setup replace the supercharged setup without much changeover? I certainly can get along without the extra horsepower it provides and I can get a low mile setup much more easily from a regular Buick than the supercharged setup in the Ultra. I know the drive axles would need to be changed also, but how about the computer, sensors, etc....? That is where I need some advice from everyone out there, thanks Don.