Welcome to the board Sam, mines an ice cold Stella
I would say in my experience that your budget may be a little lean to get you what you want, that figure is more SS country.
Lots of info on SL`s here
WWW.900sl.com Cylinder stud problems should have been resolved on most early bikes now, unless its been standing around
I came from Jap bikes to dukes and was not sure when I first got my SL but the whole Ducati V twin thing grows on you, and there is no nicer sound than a open pipe duke on full chat.
As for maintenance, look for bikes with some history etc but on the whole they seem to be owned by people who love them, but beware a neglected bike that may seem a bargain but can soon become a money pit.
Good luck in your quest and keep an eye on Ebay as they come up for sale on there quite often
Cheers
Ian