Hi Richard
There is a facebook site for the Buckland as well that may be helpful, sorry don't know the site name as don't do Facebook. Though in the post on here there is a link somewhere.
The trouble with the Buckland is it has no roof to help with strength when removing body from frame. I dont know how good your ash frame is, but if weak you will have some problems. I did similar with a Riley topless body, I took the doors off before removing body, bought a sheet of ply, cut 2 pieces to fit on the inside of the frame and screwed these into place with at least 8 screws, this kept the door frames in place, I also then cut section of ply to fit across these 2 peices and screwed these to the door sections using battens there by making an I section, You could then make some more bracing using 2x1 section from these running diagonally from the centre of the I section to the rear corners. It was a guestimate as to where to mount these when I did mine, but it worked. I placed the body on some 3x4 timber to take the place of chassis once it was removed, just make sure it is square and level.
Not sure how much sense that makes.
If you have access to you tube or the like, if you look up some Hotrod/ Resto shows where they take the body off a steel car and they brace them with a frame it will give you an idea as to the wood frame to use. (whoops I said HOTROD on the AC site, 40 lashes for me at least)
Good luck with the resto.
Gary