I installed some "racing" seats in a customers 2007 350z about 6 months ago, and bought their factory buckets for $50. The plan at the time was to make waiting room chairs but since I scored this Datsun I think my plan has changed. I have a welder, and know enough to get myself into trouble so I'm going that route.
I took a picture when I was sizing them up. I removed the risers and all the mounting hardware from the rails of the 350z seats when I installed their new ones, but the adjuster rails are still there. The 720 seat rails are 15" on center, and the 350z seat rails are 17.5" The 350z seats also need to be lifted a few inches so the bottoms will fall at about the same hight as the factory ones... Its not quite a "piece of cake" but after looking it over it shouldn't get too crazy!