Your plan will cost ~ double the $4000 that the OP has to spend. I would be surprised if you got out for less than $5000 for just the SAS. And that's if you figure out the geometry correctly the first time which happens about never. Steering conversion, suspension conversion, new driveline and all the steering arms and heim joints, new bracketry, axle shafts, new diff, gears, all the bearings, locker for the front, leafs (or coils), hubs, front locker, lots of expensive custom labor or a nice garage of your own, lots of free time and thousands in tools and fab machinery, and of course the axle housing itself.
Someone who hasn't really wheeled their IFS much yet would really be jumping into the deep end on an SAS. It's like when I used to sell people all the top of the line snowboard equipment and clothes and everything only to see them later that day learning how to ride on the bunny slope. I still say regear the front and rear and throw in a rear locker. You can get many years of use out of that set up and then decide to go more hardcore down the road.
You can also get a '79-'85 Yota pickup (or a used Heep) for less than $4000 usually and they already have SFAs. Why not build a true trail rig/rock crawler from a better platform to begin with? IMO, 3rd gens make great expedition vehicles, but not such great hardcore offroaders, lack of a roll cage being one key factor.
