Literally everything you mentioned is exactly what I wanted to do that truck when I saw it. I rebuilt and lifted the floor in my orange 85 and it was kind of a pain in the ass.
If the floor is solid in that truck, I probably wouldn’t touch it.
I’d Build a mount and skid plate for for the tank under the floor at the back, lower the shock mount and move the sliders and bumpers down. It’s quite a bit of work no matter how you slice it.
If you’re worried about lowering the mount because of shock length you could always move the tabs on your axle to the back instead of on top