MG: Those are S10 springs. This truck will be Fran's and she won't be hauling anything too heavy. The front spring perches were made from 3.5 inch square steel tubing. They are kinda ugly, but I don't think they will break! (Nobody will see them once the box and running boards are on).
Chris: the driveshaft was a bit of a challenge. Originally the truck was torque tube. The transmission I have is a SM420, which is a short tranny so a long one piece or a two piece driveshaft was needed. Long 1 piece shafts with a slip yoke are hard to find! I ended up installing a steady bearing with a two piece shaft from a 70's 4x4.