What is the intended use for the truck?
I purchased my '85 Extended Cab truck with a 3.5" Pro Comp lift that included blocks in the rear. At that point it had 32 inch tires and was otherwise stock, but performed ok and I did quite a few of the Moab trials with this setup. Then I stepped it up to a 4.5" Superlift that eliminated the blocks in the rear. The front Superlift springs actually flexed reasonably well, but the rear springs had almost no travel which translated into being really stable for climbing in Moab. With the Superlift setup I moved up to 33 inch tires, lockers, 4.88 differential gears, and a single 4.70:1 transfer case and it performed extremely well off road. After a few seasons, I replaced the rear springs with Alcans and a short block and it improved the suspension travel and ride quite a bit. I always ran OEM steering with these setups and only extended the link that runs between the frame and bracket on the front axle.
My current rig is an '89 4Runner that is running Alcan springs all the way around. OME (as previously suggested) is possibly a better value and an excellent project, but Alcan is an option that can give you a better ride and more travel because it's based on your individual specifications. I think the Alcan standard lift for Toyota's extends the rear springs by 5 inches so you'd have to install another spring hanger.
If you're not planning to change the differential gears I would recommend that you not exceed 32 inch tires. When I stepped up to 33 inch tires I made a quick jump from the 4.10 to 4.88 gears.