I did a quick google search and found a ton of information on it. I believe you can swap it over, but on some of these motors the accessories like the alternator are on the opposite side of the engine, so you'll need to get the accessories and brackets from a RWD 3.8.
The intake is also facing backwards instead of forwards. They are great engines, and some were even supercharged, but there would be a lot of messing around to get it to RWD. Not that it can't be done, but maybe you could find a RWD 3.8 instead, that would be much much easier. To me it wouldn't be worth the hassle, as I doubt it would be very cheap in the long run.
Apparently the flexplate is different as well. I believe a 700R4 should bolt right up otherwise, but don't quote me on that.
There are tons of other forums discussing this, I was reading some of them. Some of the F-body forums are a great resource for this.