Those are pretty small seats for a full size truck.
Easiest way would be to use your upright brackets off your bench, for the outer sides of the S- seats & then you'd have to find a set of inner uprights from a set of fullsize buckets. Once you have those, the buckets should bolt to 'em, with little or no modification.
Then you have to drill the holes in the floor for the inner brackets. Weld plates or use LARGE washers on the bottom side of the floor pan where the new bolts are.
I think that you'd be better off with proper buckets, or a 60/40, from a fullsize. I don't think that the s- seats would look 'right'. Same amount of work to install. But, that's me. The right seats are not that hard to find, & the fitment would probably create a lot less headaches.
I've seen pretty nice seats, non-electric, in cloth, for these trucks at the wreckers for around $100.00. Or less. Add $50.00 to $75.00 for the consoles.