Austin,
Why couldn't you use these seats? It appears to me that all of the stuff on the left side (as we see it) needs to be removed to get to a flat surface. It appears to all be metal but I can't tell it's function from the picture. It would seem that once all of this is removed then a piece of flat stock could be inserted on that side in replacement. It could be bolted in or tack welded would be better.
Then if need be you could run flat stock from side to side in order to give you something to attach the frame rails to.
If you like these seats I wouldn't give up on them. Make them work and fab something up to install them.
Sorry they aren't a direct bolt in but that doesn't mean they won't go in. Actually. I thought I read somewhere once that the only direct bolt in seats for a Samurai were Samurai seats. Anything else would need slight to more fabrication for installation.
Don't settle for anything less than what you really want otherwise in the end you will be disappointed... J/M $.02
Tux,,,