Advice on buying a 1999 Porsche 911

My dad is looking at buying a 1999 911 and wants me to do some research on their history and if they have any common issues to look out for. Any thing to look out for or work to make sure has already been done on it? It's got 65,xxx miles 6 speed manual convertible. That's all I know about it at the moment but I can find out more if you folk need specifics! Thanks in advance! via /r/cars http://ift.tt/2sAMDfi