ok simple things first...
the wings are correct for your year/model as around '69 the lights were moved into the wings and you don't have a vent in the passenger wing for the heater blower as the S3 has so keep them
you have a single wiper motor behind a panel on the left of the dash/bulkhead
your bulkhead may well be repairable, A posts, feet, footwells and that upper rot section can all be got (you probably have more rot you haven't photo'd though) last year i rebuilt a '65 2a bulkhead with similar amounts of rot and the only sections i bought were one foot and a pair of les cromies footwells (the best available) all rebuilt, media blasted and painted for about 150-175quid in materials and parts (labour/painting was my own)
there's not much you can't get in the way of chassis components (it's really worth you joining the S2 club,insurance discount alone pays for the membership fee for me) in pattern parts, i've fitted outriggers, crossmembers and dumbirons (i have a 1960/61 i think here at the moment that i'll be replacing the dumbirons on for a customer and will be getting his bulkhead to repair when it is removed)
door skins can be got, as can doorframe sections to allow repairs, tub skins can be got (there are subtle differences between the S2 and S3 tubs, again the S2 forum will give you pointers)
you have the correct sills for your year motor, i think Searles were "only" suppliers of your motor, i think they did or commisioned conversions at one time but i can't say if yours was ever converted, Searles rings a bell somewhere to do with carawagon conversions (it's just a quiet bell somewhere in the background so i could be wrong)
the rear door isn't much of a problem, i have one sat in my garage and there's plenty about but there are slight differences through the years i believe
it's a little strange that Clifton says yours is an export model but it's not unheard of, failed contracts or an ex pat' bought it whilst living abroad and brought it back when they returned but unlikely with the Searle badge, it could be another little bit of history to find
the BP and Michelin stickers suggest it was owned by a garage at one time and was possibly used as a runaround for the business (or it could have just been an owner who liked stickers
)
i'd like to see a few photos of the cab area/dashboard/heater/inside door panels/seats and a clear photo of the front of the vehicle if possible (i know, i'm a pain
)
just one little thing i noticed, there seems to be a buffer/marker light in the offside wing above the Michelin sticker (can see what looks to be wires going to it from one of the under bonnet shots) there doesn't appear to be one in the nearside wing and it's the wrong place to be a buffer, any idea what it is that i'm talking about ??
ok that all looks a little random the way it's laid out/written but that's the way my thoughts flow
it looks like it'll be an interesting project and as said before by someone else it shouldn't cost you 2k to get it back on the road, my '65 109 so far hasn't exceeded 1.5k including buying it because i took my time gathering parts/paint and i've changed my diffs and engine as well, rebuilt both dumbirons replaced a couple of outriggers and replaced the rear crossmember, i've just bought a full set of NOS springs and shocks with a few other bits which took two years to appear at a time/price that i could afford or was prepared to pay and i'm still under that 1.5k, i've been driving it for around 6 months now, owned it for two years
just take your time, the only time these things cost money is if you have a rare one that has year specific parts and it has to be put back to exactly as it was from the factory, the expensive ones are the early Series2's from '58 up to about '61/'63 after that things generally settled down with development/production, landrovers were always a partsbin build/production to a great extent so they used what the suppliers could supply or what was on the shelf, especially in the early days of the S2/2a
hope this helps you with your decision (i hope you take it on as a project
)
Cheers
Pete
p.s.
pictures of my 109 (Big Ears) rebuild
http://s259.photobucket.com/albums/hh311/NiteMare_08/My 1965 109/