I'm with Brian - what you choose need to match with everything else that you have + what do you want the car to behave.
I heard many times that 964 cam will create longer top end power, and the GT-2 evo cam even more so; relative to the SC cam (which is the same as carrera cam).
Having said that, when mine was still CIS, I don't feel power drops off even at 6000 rpm.
Have just Megasquirted my car and kept the same cam. But haven't had a chance to really test/drive her yet - have to wait till the white stuff is gone.
87 930 K27HFS/B&B/Twin-Plug... Megasquirted