I'm surfing up junkyards, trying to find me a supercharged engine and HD tranny for my '92 Bonneville N/A.

I found a Park Avenue engine for $750 and when I searched for a '97 engine, it came up with a lot more, for cheaper!

My questions are: How interchangable are the 3800 V6s with my car? Will ANY 3800 V6, charged or not, fit into my car, just like my 3800 NA does? What about the transmissions? Will the 4T60-E, 65-E, etc... fit with any of the 3800s?

For a direct swap you will want a 92-94 NA motor from almost any of the 3800 cars, the tranmission in your car will be a 92-98 NA trans with the proper gear ratio. Most likely the listings will show 92-95 for the trans though.

After that..you'd be custom and need to work over a newer wiring harness and change to a newer pcm etc etc. For someone knowing the quirks, it'* not too bad, but it'* custom.

So what all would I have to change if I got a 95-97 supercharged motor? Just change up the trans and wiring? Would my engine mounts line up and whatnot?

You'd aim for 98+ to have the best parts available with the best pcm support. 97 is ok, but the pcm change happened in 98 and the trans in 97 was just slightly different from the 98 as well.

You'd need engine wiring harness.
Complete engine including alt/ps pump/AC/mount
Complete trans including axles and mounts

From there you'd need the pcm reprogrammed to remove the couple things it has in it that your 92 wouldn't have passing through it. Like fuel level (97+ it goes through the pcm, your year doesn't).
And you'd need to mofify the firewall pinouts where the engine harness feeds into the interior for a few wiring changes over the years.

All the mounts will fit in your subframe etc.

Where would I go to get a PCM reprogrammed? For not too much money...

So I should aim for a 98+ parts car because they're better? the $750 engine is a 97 I think.

Also, wouldn't I need to convert to OBD2? My car is OBD1 and the engine came from an OBD2 car.

With the new pcm, you'd gain OBDII.

See...there'* tons of stuff that needs to be considered. PCM could be done by Intense-Racing. They have experience with this stuff.

So it would just be easier to buy the whole wrecked car and change ove all the internals to my car so that it'* a 97 bonnie trapped in a 92 body? I would just buy a newer bonnie, but the ones I found are expensive!

You could do it with ,Engine wiring harness, PCM, Engine, Trans and a couple other misc connectors or parts. You don't need the whole car or interior harness etc. That stuff we can help you with. A whole wrecked car would be nice though.

Well, I'll have to look into the whole wrecked car deal. Because with that, I can swap all that'* needed.

Would getting the wrecked car and swapping parts be better? Maybe my car can finally have specialties, like dual exhaust.

If you went through Morad Part Company, they'd typically have complete setups ready with everything you needed.