Feasibility of converting 110 to 90 soft-top

I have the option of buying a cat B 110 TD5 county which suffered vandal fire damage in the cab (it had just passed it's MOT!). I already have a TD5 110 and want to use most of it as a donor vehicle for spares, but would also like a 90 soft top.

If I was to obtain a galv 90 chassis, dose anyone know what major parts are different mechanically. Also does anyone know if it would be possible to re-register the car for road use if it had a new chassis and a new interior?

As far as I'm aware you cant. Someone might be along to correct me shortly. But a chassis is just like swapping over consumables in the eyes of the DVLA. What you proposing is major structural etc and would set alarms off that it' a ringer. A cat b isn'
Allowed back on the road either so no chance of that.
Mechanically engine gearbox axles etc will fit. Rear prop exhaust and a few other bits will be too long

You may be right - I am not doing it to sell on but the sentiment still remains. I did find this though....https://www.adrianflux.co.uk/category-b-insurance/

You would struggle to get a cat B 110 back on the road if you just repaired it, but if you also converted it to a 90 I would say that you have no chance at all.

So presumably I'd be looking at a Q plate.

I think that you would be looking at IVA / SVA type approval first, which would bring with it a whole world of grief. You would be better repairing an existing vehicle.