I found a 2003 Chevy Impala with a blown series II 3800 V6. I have a 1997 Buick Regal with a series II 3800 V6 supercharged. I already know that I would have to swap the intakes. But will my motor work in the newer car?

Most likely, however the engine has a lower compression ratio, and will make less power. I don't know what downstream effects there will be from the difference. It may be good to widen your search to include series 3 NA, as the blocks are tthe same usually, you would simply swap your intake system over usually.

Yeah it would work, if you have a decent motor already to swap in I'd not bother trying to buy another just for a tad more power..
Yeah your compression ratio will go from 9.4:1 to 8.5:1, but if the car is just an average daily driver it will be fine..
Make sure to swap over wiring harness for the donor motor, and the PCM...

I've seen it work before with a 96 Park Ave that use to be Supercharged.

Whoa wait, you can't just swap supercharger and intake manifolds. You must also swap heads, tensioners, idler pulleys, brackets etc. Or otherwise known as a top swap. Then it requires custom tuning.

Hmm, at first it sounded like he wanted to swap over the whole motor..
If so he should just swap the whole SC Motor and Tranny over...

If he is wanting to take his L67 and put it in a chassis with just the L36, he needs the engine, trans, HARNESS from a 2003 L67 Impala and a ECU L67 from a 2003 Impala.