ok, so you have a sidekick. the rear already has a 3 link set up, why not keep this set up, as there is a base starting point. upper Y link will control lateral movement, and also pinion angle. lowers will control fore aft movement. maybe make some custom extended lower arms to allow for more travel in a bigger radius.
i'm not familiar with Dana diffs, i'm in Australia. but i figure rear has centre pumpkin.
with front, if going coils, maybe try an easy 3 link set up also. 2 lower arms like the rear, and a panhard bar front top of diff to chassis. maybe you could even use one of the original lower A arm mounts for the panhard, and just beef it.
front should have a right hand off set pumpkin, right? even if the front DS is at a bit of an angle to the side, i dont think it should matter a whole head, and i only use 4wd off road when i really need it. it doesnt even come close to snowing here. i can live with slight vibrations if the trade off is full size solids under a sidekick.
you might have to look at the sump clearance also, when the front diff is moving through its full travel motion, will the front DS touch the sump?
and with full size diffs, and maybe 33"s, some form of power steer may be on the cards, such as a yota power steer set up. or similar.
ok, i've rambled on a bit about nothing really, so havent yet answered your questions. with the deflection of the DS or U Joints, i have no idea, and as with transfer cases, just get some crawler gears, or a kicker set up, or dual cases with a sammy case. but i suppose theres not much room for a dual case set up on a SWB.
anyhow, good luck, and make sure you post up pics and tech if you do decide to go ahead, and also when you figure things out.
Cheers.