Like SenorNoob said, seat tracks from an 83-88 Regular cab Ranger with buckets or 60/40 split bench. Attach your chosen seats to those. For a factory seat, that is probably the best option. Alternatively some companies may offer a racing seat base that fits the truck, then attach universal sliders and seats to those.
For period correctness you could find buckets from 83-88 Ranger or BII. If you want something a little more supportive and sporty, look to the fox (or earlier) Mustangs. The problem with many newer seats is that they are high back and/or thick, that pushes them forward and there isn't a lot of room in a Ranger to begin with. Many of those 80s Ford bucket seats used the same mounting pattern on the base, so the tracks will bolt on. Those that don't can usually be done with a simple bracket between the seat base and Ranger tracks.
Another good option if you can find them might be some 70s-80s-90s FloFit or Recaro seats. They may require more work to adapt, but should fit well thanks to their thin seat back and base.
The FloFits were used by Saleen in the 80s foxbodys and they also used them in a handful of first gen regular cab Rangers, but I think they were discontinued in the late 80s. Also a lost sold in aftermarket. Not easy to find, but are out there. I scored a used set locally earlier this year.
Recaro LSX (IIRC) were used used in the pace car Mustangs, a lot of other cars, and a lot sold in aftermarket. Practically the same dimensions as FloFit and arguably the better of the two. These are fairly easy to find in all sorts of conditions and pricing to match.