Actually, you need a new t-case. The Crawlers gears don't mount in the SJ-410 t-case, but on the plus side a Samurai T-Case is a bolt in replacement. Your e-brake will even swap over without a problem. Hold onto your old t-case though, it has 10% lower high and low range gears then the stock Samurai t-case. Making it perfect for someone running 235/75R15 tires.
Your axles are also incompatible with anything Samurai and hard to find replacements for. Your spring pads are 1.5" closer together on each side, so if you swap some Samurai axles on you will need to cut and re-weld all the spring perches.
As for SJ-410 crawlers, that is what I have. Still run the stock 1.0l motor and 4 speed, thing runs like a champ. No stalling issues either due to the side-draft carb. If I was going through the trouble of swapping motors I would go with a 1.6l or 2.0 rather then the 1.3, which only nets you 20hp. Of course, that is 40% more power...