Per George Lowden's own site at this page, a buff label means it was made in Japan between 1980 and 1985.
IIRC, the old G7 model is roughly equivalent to the present O32 - both have spruce tops, but G7 was ovangkol back/sides where the O32 is East Indian rosewood. Lowden currently want around £2500 for a new O32-12. Last time I saw one of those mentioned on the Cult of Lowden, they wanted around £1800 for it - certainly a stock O32 in very good condition would be worth £1500, and a 12-string would be worth a bit more. It's difficult to guess a price for a Lowden 12-string though, because there are so few around.
If I had a few more quid spare, I'd definitely be in the market for it! Trouble is, I've recently been building up on PA and recording gear, so I don't know if I could get that pas Mission Control. ;-) Plus we're in the process of buying a new house. Still though, if you're in the UK then sling a post on here when you've got an idea how much you'd want for it, and I'll see how I'm set then.
But as ThreeSheds says, the Cult of Lowden is definitely the best place to ask. You might also find yourself a buyer on there, since there are a few "completists" on there who have just about every model ever made!