I finished building my 110 station wagon last year. the chassis are the same, like has been said just the addition of the bolt-on "station wagon" crossmember.
I built mine from scratch, so had to source all the parts. rear tub i got from Autocraft4x4_midlands on ebay, MArtin is the chap, got a 2006 rear tub for £300.
pair of B pillars off of the same vehicle for £125, and they were mint!
roof panel and rear end door are all the same so the ones from your hard top will fit. you'll also need a pair of side doors, these can be quite costly (to get decent non-rotted ones)
Best bet is keep scouring ebay, get the bits all together until you've got the whole "kit" and then take a weekend to do the job.
don't forget the interior trim (if you want it)... 110 rear sliding window trim panels are quite cheap, as everyone wants 90 ones, but if you fit series side panels then you won't really need them. there's a few bits of trim over the middle and front doors, I picked mine up on ebay for not much money.
Some middle tow seats (again, got mine from ebay, late Td5 60/40 ones for about £30) mose expensive and akward bits to get were the locks the hold the seats in place (For the 60/40 split seats)
Easy job though, like has been said, just nuts & bolts (and some lifting!)