Buncha 2.7 haters in here.
My 1977 91S 2.7 has 97k on it, and has no issues, and no evidence of being rebuilt.
As an actual owner of a car with the "much maligned" 2.7 engine, I can say mine is great. On my car, the thermal reactors were removed about 15 years ago, and it's been maintained well. It also has the updated tensioners, and turbo valve covers.
I bought it for 9k, pulled the engine, spent $400 on gaskets and **** (fixed the common leaks for all 911 engines), put it back in, and it's been turn-key reliable for the entire summer.
As you can see, I baby it.
1977 911S auto-x and speed run. - YouTube
(one of 9 runs that day--did not even have to add oil)
Also, for all the beard-yanking going on regarding the PPI:
http://forums.pelicanparts.com/porsche-911-technical-forum/695802-fess-up-did-you-get-ppi-before-buying.html
Yeah.
In a nutshell, this is an old, kinda weird air cooled car...not rocket science. If you want it, get it. If it goes bad, it's going to be expensive.
I sometimes get the impression that sometimes people can parrot things about the "bad" 2.7 engine over the internet, without having actually dealt with it themselves.
Now my rant is over.