As far as ideas for other swaps, here's a short list:
1) 20B, turbo or NA
2) 3.8L turbo Buick Grand National engine. Downside: Automatic only.
3) 4.3L Vortech. With a T-56 like I'm going to do, mileage should be awesome. I know guys with LT-1s and T-56s that are getting 30 mpg or more from an FC with it. Most things like rings, pistons, connecting rods, etc are interchangeable with 5.7L motors.
4) Anybody consider one of the big Porsche 4 cyls? Don't they go up to 3.0L?
5) 3.5L Nissan V6, want to say it's coded 35VQ or something like that. You can find that engine in the 350Z as well as a bunch of different mini-vans(!) and the Maxima.
6) The aforementioned 2.3L turbo.
7) I wouldn't mind getting the 4.0L Lexus V8 out of the SC400, or the 4.3L from the SC430.