Sounds like a Faulty Towers episode....oh wait, you're in England - sorry!
I guess he's playing a kind of wierd game of hard to get. Or maybe he's read this board and thought you were Nostatic (sorry Todd - couldn't resist!).
I agree that not being able to test the engine under load is an issue. Can you talk to/visit the wrench that did the rebuild - does he have all receipts?
And what is it about his selling process that requires
months of negotiations? Once I decided to buy my car, it took oh, maybe five minutes - only because I didn't want to seem too eager.
FWIW: Like DR. Sopp, the first Porsche I looked at (and bought) was, uh, the first Porsche I looked at. And the owner was a bit on the particular side (big hint - all garage items in plastic boxes with p-touch contents labels on the outside) - so I declined to drive it at first. Only with his insistence did I venture behind the wheel and I was so nervous I doubt that I benefited from the experience (in a mechanical evaluation sense), other than I knew I had to have one.
I'm curious to know how this turns out...