Educate me on earlier 911's (70-80's)

I was looking through the car lounge and saw a post about someone picking up a 1977 911. It got me to thinking, what are the differences between the 71-86 911’s? They seem to be the most reasonably priced ones so what are the main differences? What are the operating costs? General feeling on picking up say a 74 911 and droping the 3.2 in it? Could this be a DD? Give me any input…

edit: Found this but still, what are diff?: http://en.wikipedia.org/wiki/Porsche_911

Run like hell from the CIS injection ones. You def. want a car with the 3.2 motronic injection. Plus, the handling of those gen. 911’s are very so-so. They’re dangerously tail happy. I’d be prepared to spend a lot on upgrades, suspension wise. There’s a reason they’re so much cheaper to get into. Personally I’d save a little longer and get a little newer model, like and 86+.

youll never get one

They all leak oil.
Stay away from the 2.7 litre.
Watch out for rust.
They are a blast to drive.
My 1971 was about 200hp and about 2000#.

get an SC and do the upgrades it will run well for a long time.