911 Buyers Guide.
 

I'm new to the forum and i am new to Porsche so have mercy.

I am beginning my search for a 70's through late 80's 911.
what are the most desirable models through that range.
i would also entertain any information on pitfalls or gotcha's such as the magnesium block models, etc..

any information would be appreciated.including websites or books that provide this information.