Talk about coincidences, a fellow landrover club member has an '82 R65LS - I thought they were rare!

Anyway, he's emigrating to pastures far warmer and sunnier than Yorkshire and has asked me if I'm interested in buying his LS.
The problem is that its in boxes! He stripped it down to restore it a few years ago, and as often happens, he never got around to finishing the job, so I now have the chance of buying a 42k mile LS - conveniently flat packed

My initial thought was to refuse it as space is tight as it is, but the wife is happy for me to get it either as a spares bike, or to rebuild and sell on at a profit.
I have no idea how much he's going to ask for it, but I was wondering what its worth? Its complete, partially overhauled (he's an experienced mechanic) but I haven't seen the bike and have no idea what its like. I'm thinking of offering him £400-500 for it - is that reasonable? He has said that he'll break the bike for parts if he can't sell it complete for a 'reasonable' price...
Thanks for your thoughts!