I am confused. From your picture, I don't see where you left "about one inch all the way around".
I can see the top of the rocker panel (no floor board metal there).
The toe board is completely gone.
It looks to me that all of the supports for the floor is there and in good condition. The new floor just lays on top and is spot welded to the supports below. You should already be aware of that since you had to drill/grind the old spot welds to remove the old floor.
Your challenge will be dealing with where the floor meets the inner cowl (kick panel). I trimmed off the flange on the floor patch panel and ran a bead of weld from front to back.
Don't be surprised if there is a gap in the middle between your two patch panels. For some reason the manufacturers often don't give you enough metal to meet in the middle.
I butt welded the rear edge of the patch panels to the existing floor.
Carl
