Any of those cartridge choices are an improvement over the Blue Point, which wasnt bad for its price at the time. They will all work fine with the GCPH which has plenty of gain and loading options. Your Project 6 is a decent turntable that is underrated in my opinion. I have one along with an Oracle Delphi and the difference is not earth shattering, the Oracle being somewhat better refined and quieter and much better looking. If you were going to spend $2500 then the VPI classic is an obvious choice for a new turntable, or one of the clearaudio's with a magnetic bearing. Those are both ridgid tables. If you are looking for a suspended table, try the Sota Sapphire.