I'm planning on doing the exact same with my '86 sammy, I have a '82 3tc with the T50 speed. From much searching on the net, this is what I've found.
The 3tc/5speed is quite a bit longer than the zuki engine/tranny, requiring the engine to be mounted a bit further ahead, and possibley moving the t-case back a bit, to allow adequate driveshaft length. Weight is probably around 100 pounds more or so than stock. Gear ratios in the t50 are very close to zuki, not quite as low in 1st, but close. Others are very close. Easy to bump up power in the 3tc, without going nuts. It should be pretty easy to get 110 hp or so, without much expense and without loosing low-end torque.
To my way of thinking, it is the best Toyota engine to use...fairly light, more power, but not so much to stress running gear, readilly available parts in junkyards, etc., smaller than 20r/22r, and easier to cool. A grat reputation for reliability.
What I think would be truly ideal would be to find a way to adapt the 3tc to a 2wd sidekick 5 speed ( stronger than sammy, short, and set for divorced t-case ). using the 3tc clutch, bellhouseing, etc. But I've reached a dead-end so far. There is an outfit in Australia ( Dellow conversions ) I've been trying to e-mail to see if they make an adaptor, but my e-mails have not gone through ( maybe 'cause I use the 'putor at work, and it may have "blockers"

). Oh, I plan on using the "doner" Corolla hydraulic clutch, others have done the same. I"m new to this site, not sure of some of the rules, so if you pm me, I can refer you to other sites that have info. I don't want to step on any toes on this site. Also, with a $100 adaptor plate a 3tc engine/clutch/bellhousing can be adapter to the stronger "W" series 5 speeds, used in celica's & trucks. But they are still long, however. Mark