You could probably find a thread here somewhere on this. Here are some options the dana 44 does not have a 4.63 ratio. The closest you could get is a 4.55 not close enough. Toyota used to have 4.63 in 1st gen 4x4 BUT extremely hard to find . 4.90 is your best option in rear because almost everyone makes a 4.88 and you will have no trouble with those. Your best bet is find some used 4.90 from xterra in wreaking yard.
As far as axles go, that is up to you and how much money you want to spend. I went with a 1985 toyota 4 runner axle.Mainly because I had it sitting in garage so I spent very little money on my SAS. It was quite a bit of work because that is a pass. side drop that I had to flip to drivers side. The dana 44 is what most people use.Steve with RuggedRocks.com has a new diamond axle that uses a nissan 3rd member(HUGE advantage). I do not remember what the total cost is or what steering knuckles he uses but if you call or email him he will let you know.He was thinking of making a front link set up awhile back. I am not sure where he currently stands on that project,ask see what he says. Trailgear.com has a nice axle called Rock Assault (for tacoma's). Those are a few options I am sure there are more,but these are what I had found.
On link set ups again there are endless options www.ruffstuffspecialties.com is a company I have used quite a bit with a couple different builds. They have high quality parts and sell complete link set ups. They ship out same day to next day which is a big plus.I have dealt with a few other fab companies and have been VERY disappointed when I have not recieved what I ordered after 10 days. After a call to manager I found out they were back ordered for min.3-4 weeks.
Check this out NissanNut.com they have alot of info. I hope that helps . Good luck