Regarding the driver seat sliders, I put my seat belts below the sliders, and I used a 3/4" or so spacer to lift the sliders off the floor. I found that because the fiberglass of the floor isn't flat, the mechanism was binding and worked very poorly, was impossible to move the seat. After raising the sliders up on the spacers, it now works poorly. Which is an improvement over very poorly/not working.

For the passenger seat, each box section tube has sets of holes. before you install the tube to to the seat bottom, you install the 4 bolts that will be long enough to go through the floor, through the 4 large holes first, so that the head of the bolts will be inside the tube. Then you take that assembly, and mate it to the bottom of the seat, and put the supplied bolts up through the bottom of the tube, and thread into the seat bottom. Call me if you want to go through it over facetime or something. I'm available mostly any time.
I plan to ditch the seat sliders for something more....less poorly functioning. I guess I need to measure the distance between the holes on the seat bottoms, unless someone has that handy.