Though in theory a SA truck would be less expensive, you still have a bunch of work to do. Crossover steering and new steering box, beefing the front hangers, leaf springs to actually be able to take advantage of the articulation, you will really want better brakes (which requires widening the axle somehow - either wheel adapters, or another wide-axle kit such as the one Sky sells which was originally developed by Front Range Offroad Fabrication). Then you need a wider rear axle to match - or put wheel adapters there too. Either will need revised shock towers; Ford F250 $12.50 towers are hard to beat. Either requires cubic dollars or the ability to weld yourself, take your pick.

You would be well advised to go with beefier birfields with either option, but this can be deferred. Until they bust in the middle of the night in the rain. But that's the same with either option.

You can see that about the only difference is, the SA truck comes with the axle, and offers more up-travel. Everything else is just about as much work. Axles run around $200-350 hub to hub, so there is not much cost difference. Clean, "low" mileage EFI '85s are getting rare as hen's teeth; not so much later IFS rigs in all sorts of shapes and sizes. Take your pick, basically.

Hope that helps. Look to spend between $2K-$3.5K or so total. More if you want hell-for-stout, plus high pinion, plus ...