I've been considering doing the same.
I thought about putting a 2wd case in, and the sami tcase behind it. This way i'd have plenty of room. I need to find the gear ratios in high and low of a stock sidekick case, then compare that to a 4.1 to 1 or 6.1 to 1 sami box and see. I'd be looking for about 15 to 20% reduction in high range i'd assume to run 33's to 35's (swapping out axles of course).