The bike in question sounds priced at about double what it is worth; by the time you've cleaned up various and then gone through a recommission period and the relating repairs and fixes. I'd expect something restored, pristine and the bugs shaken out for that money.
Your feelings and comments are very much the same as my own.
Found a 60 SR today which is with a local dealer and thought it might one to go for but no price was advertised.
However, on ringing up to enquire about it his first comment before any detail on the bike was discussed was that the reg No alone is worth £2K and then when we finally got around to the asking price for the bike it was £7K!!!!!!!!!!!!!
It would seem that since he values the reg No at £2K he has simply added that value to the bike which in reality should be valued between £5 to £5.5K?
So it seems now that if you go for a bike which has an original reg that you have to pay an additional premium for that as well?