I'm not sure if I have cocked up here?
I have a series 3 station wagon with a full size rear door and very poor sliding side windows.
I spotted some 2nd hand cheap non sliding sides from a series 3 that I guess must of have had a catflap/tailgate type arrangement and bought them without thinking really (as I thought it would save me a job)

So the question is, will a full size door fit with catflap/tailgate sides... The full size door has a top hinge so the holes for that would be missing on those sides or is it just a case of drilling a couple of holes?? Or are they just not compatible?

Should think they’re compatible but as you say need a few extra holes, @lynall would know better
I would repair the windows if it’s just the runners need replacing

The series three club used to do plastic runners for the side windows, not sure if they are still going?
I think rear door will fit no worries apart from hinge holes, might be some support/reinforcing needed for said hinges?

https://www.thelandroverclub.co.uk/shop/Clubmembership/31
https://www.thelandroverclub.co.uk/window-chanel-fitting