I wouldn't touch it unless you are prone to enjoy lots of work and it is so cheap you have nothing to lose. There are still many 850 and S/V 70s running which are not badly priced in my view, and which won't be already known to have liabilities. The history which you have no way to verify directly would worry me. I am investigating rebuilding my own 850 engine (or at least the upper end) which has a bad valve. This car has been under my care for a decade. It is a big investment of time which I am only considering since I have another car and don't in any case depend absolutely on having any car. Just my own view, of course!