The only way the 8" kit will be somewhat manageable is if you also get something like the Stonecrusher steering linkage on it. Otherwise it's gonna handle like ass (to the point of being dangerous IMO).
I think your driveshafts will be OK, though I could see needing to clearance your front yoke at the t-case a bit for clearance at full-droop if you have a manual trans in your '86.
I'm not even sure the stonecrusher kit on a 8" kit would produce good driving characteristics. I had one with a 6" kit, AND a FA600 and it drove like absolute crap. Worse than 6" of lift with a 4" drop pitman arm on stock linkage. I couldn't stay in a lane if the pavement was *featured* in any way what so ever. Too much difference between the lift height of the kit/coils versus the droped steering linkage (was a difference of around 2.5"-3")
OP, go with a 6 SJ kit, an FA600 arm or *modified* Superlift Superrunner steeging setup (mod the centerlink down 2-2.5").
If you still find you need a bit extra height to help clear the 35s, trim your fenders and/or run washers (orskip straight to 8" coils and be done with it).Then sell the 6"ers...
Good Luck Man!
If you need persuasion that 35's will fit, take a look at my truck in my build thread or elsewhere. I am at 6.5" of lift with 33's and have a ton of fender room (though I know the first gens have less fender room, I have more than enough for 35's, albeit some trimming of the inner fender is unavoidable no matter what generation truck).