Nice write up, don't recall the flat floor pans being available when I did mine. I used the pickup front floor section and had to flatten the aft part.
I didn't have to go back as far as you.
I had to replace the longitudinal under supports and rebuild the rocket boxes as well.
Basket case. Took me some time to get all lined up. (Wet noodle)
I used herculiner and has held up well without extreme abuse.