HI it took me a while overall but the longest bit was waiting for about a week for a sheetmetal workers to bend the ally.best to get it cut to size and bent up by same workshop.
i took time to galvo paint the crossmembers first and properly paint the underside, once you have the bits, it can be in and out in half to 1 day
as the floor was mostly shot, i ground off the rivets from inside and punched them out, remove wheel sarrier bracket and door btm stripfloor just lifted out , there was some good bits of old floor which i reused for patches on the seatbox ends , it bends ok after annealing
I had thought the sheet metal workers could spot weld the ally channel to plate but after practising they said it would not look too good therefore
I used araldite 2015 ( very strong 2 part adhesive, google it for spec and what othere people use it for, i gt 200ml cartridge and used about half) to stick the top hat channel to floorbottom, its since carried 1/2 tonne rubble in without any probs, needs careful preparation ie light sanding and cleaning with meths, the glue goes off quick with light handling in 4 hours
the drg is in mm for the workshop, but original in inches
i used some panel sealant before placing the new floor, i havent painted the inside as the previous onwer put in some ply to cover the holes
if you pm me your email address i can send some info its too big to post