What I really want is a rig that will haul for family camping, wheel at least as well as my stock Cherokee, and tow at least 7500 lbs. Ideally I'd have a 3/4 ton Tahoe but that's a bit of a rare bird. 14 bolt swap is easy. 4L60E I guess can be built up if needed. The 1/2 ton IFS... how fragile are we talking, here? Will it stand up to 31" tires without breakage? What tends to fail?
I owned a 96 Tahoe for 3 years and then a 98 Tahoe for 10 years and a year ago I sold my 98 and bought an 80, so here are my thoughts. I really liked my Tahoes and wouldn't hesitate to get one again in the future if things change, but I wanted to get into a little more offroading and wanted a second set of doors (my Tahoes were 2-door versions) for my girls. I also had an 89 K5 Jimmy at one point.
For the Tahoe, 32s - 265/75R16 - are the stock size on lots of GMT400s, so 31s wouldn't be a problem, I wouldn't go lower than 32s though. Getting a 14 bolt would be really nice, I would probably try to get a semi-float 14 bolt w/ 6 lugs to keep things simple though. It is really difficult to change the front to 8 lugs without going SAS or maybe wheel spacers/adapters, but you are left with a relatively weak for off road use IFS unless you go SAS. I never had a problem with it though and it is nice for on the road (coming from a K5). I assume you are wanting a 4-door Tahoe (both of mine were 2-Doors) the rear seat space is much better than the 80s. Storage space behind the 2nd row is about comparable, maybe slightly better in the Tahoe. They are cheap and easy to take care of and should last a long time with proper care (have already lasted a long time really) and with the 5.7 have much better power than an 80 unless you get a supercharged 80. Offroad is a different matter. I doubt it will do as well as your stock Cherokee unless you get a lift and bigger tires and have a working rear limited slip (they tend to be flaky), but they do fairly well for such a large rig. You need about a 6 inch lift for 35s (some have done it with less, but ...) and with as long as the Tahoe is it isn't great for clearances. Going to 285/75 generally only involves a torsion crank, but that can accellerate wear on components so some people don't want to do that. They are also quite a bit wider than the Jeeps, so don't fit in a lot of places the Jeeps do and ruts tend to be the wrong size at least if there are a lot of jeeps around.
For the 80, it is a little smaller, but is still a nice ride even with the solid front axle. It takes more money to maintain but I don't feel like I will ever be left stranded. I really miss the V8 from my Tahoe, but the 80 is acceptable for me. On road it rides very smooth, not quite as nice as the Tahoe due to the solid front, but off road a stock 80 will run circles around a stock Tahoe, especially if you get the lockers with it (yay!). It is much cheaper to fit 35s on an 80 and only needs about 2.5" lift and lift kits in this range are much less expensive than for a 6" on the Tahoe; you can fit 33s (285/75R16) on it stock to get a good off road boost with only buying tires. For offroad specific accessories (skid plates, sliders, etc), the 80 has better market support, but for other items the Chevy tends to be easier to find things for.
