Why would you want to get rid of your N*? the N* engine came from a 2 peaice racing block. For less then what it would cost to drop in an SBC or LS, you can be tapping into much much more power with the N* engine.
I would recomend doing a search on PCM tuning and cam swap. There is a video on the net somewhere of a N* with swapped cams holding 14K RPM for several hours without any faillures.
Keep in mind that the N* was delibratly tammed down for the Caddilac platform doue to Cadillac's targetted customer base. (Ritered elderly people looking for luxury).
I'll see what i can digg up and post it here.
ever find this video? your sayin a stock N* holding 14k rpms?
someon said the ls3 is a near bolt in. what kind of welding needs to be done. are we just talking brackets to mount the engine?