Having owned a handful of leaf-sprung trucks, I see no need for a coilover SAS kit. I think the appropriate leafs matched to the right shocks will ride and handle as good as any truck with large tires. Simple and effective on the trail. And it will save you a fortune. I like the TG kit because it comes with the frame reinforcements already set up for the steering box. If I were to SAS, I would use the cheapest TG kit (minus the springs) and build my own spring pack using pickup rears.
FWIW, my '85 pickup with no-name lift springs in the front and chevy 63's in the rear rode way better than my '97 4runner does.