The passenger wheel well is going to be the hardest part to repair. the pitting shown suggests it all has to come out
The floors are easy and readily available. it will probably need, from those photos, inner sills and most likely outer sills...at least in the front but replace the entire section to be sure.
the front left chassis rails looks poo so might need attention, but again is pretty straight forward to replace and I believe should be available ex UK. or repair if necessary
I dont think lower bulkhead sections are available and would require the entire front end panels removed. Hit your local wrecker and see if you can find another car with similar shaped wheel well bowls, there are a few that could be grafted in You might need splash panels as well
What are the 'A' pillars like? I have some good Mk2 ones with very good scuttle sections.
The bubble isn't as bad as some and patch panels are available or build your own...but if they are available its much quicker and less frustrating to buy
No matter what you'll need to get friendly with your welder and grinder and budget about 1-1.5K on panels if you buy new and 6 months part time work ( 1 day a weekend and an evening or two a week) just on the bulkhead and floors
What the rest of the car like?
JP