I'm in the early stages of restoring an aks400. I'm hoping to find a reputable body restorer but prior to that, I want to do as much preparation as possible myself to keep the costs down.
I plan to remove the body from the chassis and transport the body to the afore mentioned body restorer. The sills, windscreen surround, top bulkhead A and B posts are all in good condition (i.e. thay all seem to be doing their job as a structure and, as yet, no signs of serious corrosion). The floors and lower bulkhead are all shot.
I've already removed the L/H rear wheel arch panel and the rear valence has been replaced some years ago.

My query is that if I cut out the floors and drill out the spot welds and remove the lower bulkhead will the body deform/twist in any way? I have to transport the body from France to the UK it's going to be a lot easier without the chassis. All doors and removable panels will be taken off therefore no point of reference for any welder if one was needed.

My other question is is there a replacement panel for this panel?

It's rusted through, in places, on the inside, along the run of the B post. It would be good to remove it and rust treat the hidden side of the B post before too much corrosion sets in.
I would be grateful for any helpful comments (Also very grateful if anyone could mention any such body restorers)

You'll need to brace the shell in some way before moving it if you cut out that much metal. Ideally, you'd leave it on the chassis, or at the very least leave the shell as intact as possible. Even then, I'd be tempted to weld some bracing in to keep everything square.

You have to be very careful with vans, especially 400s, as if you move the shell off the chassis and its not properly braced the cab roof will pull forward from the van section. All you have preventing this on a solid shell is the floors and mainly the sills, on a rotten one, or one with no sills you're almost guaranteed to have trouble there is you don't brace it up well.

If you need anything bringing over, we're coming to Normandy the first weekend in August (just for a day to treat the new lintels, before heading south for some sunshine).

Before we cut out any structual parts of our vancab,or even took the body and chassis apart, we made some temporary reinforcements as shown in the pics.
This helped to keep the body in shape. Now it shows that it worked perfectly, the doors fit like before.

Rhythm Thief and Russell many thanks for your advice. Jacqueslemac thanks very much for your offer but being summer we have loads of UK visitors (funnily enough we don'r see them in the winter!) and Gert thanks very much for taking the time to post the pictures they are very helpful, very much appreciated.