Brad, have you considered an minivan floor? Stop at a company that makes minivan handicap units, most of them cut the entire floor out in order to lower them ~6". I used to work for a company that made them and we just threw the floors to the junkyard. I'm going to put one in my '49 Sub so I have the metal for seat belt mounts. Mini van floors also have recess' for the seat hold downs. You may even be able to find a cut out with stow and gos, although those seats are not the most comfortable (had one!) The regular seats are pretty comfortable too.
