I'm no expert but that looks better when you first said the floor was bent, to me that would have meant the chassis had gone. This however is something that has come up through the floor, so not pushed anything out of shape.
We had a Cavalier and the day before its MOT was giving it a quick check over and found the passenger side carpet was soaking. Lifted it out and the floor had rusted away, being held together with the underseal.
Cut the old floor out and mig welded a new floor pan in. That when I had the use of our workshop at work.
That floor wouldn't worry me, just beat it back into shape and weld a patch over it.
Good Luck with it,
When I welded the MGB SILLS and wings I used a hand held tool that crimped the metal so the bit being welded in sat flush, rather than butt the two bits up together, Joggle tool, Not teaching you to suck eggs but it makes it a bit easier.
https://www.youtube.com/watch?v=dqe641IkQkg