The price looks OK but I'd like to know what the £35,000 was spent on. Especially given that the heat exchangers don't work and neaver have. This would suggest either that the exhaust needs changing (£1000 for a decent SS one) or that the butterfly valves are buggered.
Also you need photos of the A and B pillars also around the lights to check for rust. Also need to check on the sills, kidney areas and around the screen as these are where the 911SC rust first it seams. mind you with a recent paint job this all could be covered up.
In the recepts section look to see if the cluch has been changed or any major engine work.
Given the mileage the shocks will be shot and should be replaced. Additionally to improve the stearing the Turbo stearing kit should be added.
Good to see it's got a strut brace.
Hopefully some of this has been done in the £35,000 spent. Strange that after this sort of cash the heating does not work.
Also if it has a SS exhaust be careful as there are SS with Galvanised end exhausts out there that last about 2 years (I know because my old mechanic who will remain nameless at this stage put one on my car saying it was full SS and the only ones available - I now have a decent Porsche Specialist who replaced it for a propper sport SS one)!
I bought my 911SC through ebay about 3 years back and have had a fair bit done to it to bring her back to full life so if I can help let me know.
Hope this helps
Cheers 8)