Ok. I've been trying to do as much reading as I can about performing this swap, but besides from Calypsons SJ410k Build, I have found anyone else that has performed a 2.3L swap. But, So Far, I think this swap must be possible - Though I most likely, am forgetting about something.
For starters, Trail Tough sells a 2.0L Kit to put a Tracker 2.0 into your Samurai. So, I did some searching on Ebay to get a idea on what a Tracker 2.0 would cost, and all the Suzuki 2.0L engines that I could find were out of the Suzuki Aerio (Pre 2004). So I sent Brent at Trail Tough an email and asked him if this engine would work, and he said that the blocks are the same, but that the whole plumbing/wiring would be different.
Another guy on the board here, Calypson, had a 2.0L + Auto Tranny out of a Early Vitara. He was able to swap in a 2.3L out of a 2004+ Suzuki Aerio, because it bolted up to the Vitara 2.0 Auto tranny. Even all the 2.0 Accessories (Air Conditioning Compressor, Power Steering pump) Bolted on to the 2.3L.
Though, Would it be possible to keep the stock Samurai 5spd? It seems like you would be able to, because wouldn't the 2.0L in the later trackers be the same as the 2.0's in the Vitaras? And then from Calypsons experience, the 2.3L mounts the same as the Vitara 2.0.
Then for Wiring + Plumbing Calypson that that he used the Wiring Harness out of the same Vitara that he got the 2.0 out of, and that he also made it work with the 2.3L.
So Is it possible that you could use the Flywheel and the adapter plate for Trail Toughs 2.0L conversion kit, to put a 2.3L Aerio engine in your Samurai?