best to chop floor and sills of and see what they like the floor on my i had to cut back to wheel arches
to get all rot and rust out and then make up channels to fix floor panel to,the sills i think are easier on a 5door but i depends weatyer you nead to do inner and outer sills and what you got to weld to as a small hole
will get bigger as you grind it but you might get away with patching them i left sill covers of and covered with hammerrite
to help them last longer hope you get it sorted :)