I'd agree with Rev...
If you want to try to grab some more performance, try a spring swap. They only cost a few bucks, take a few minutes to install... I was really surprised at the difference they make.
As far as the cam... one idea might be going to the roller tipped rockers... but I wouldn't go much more aggressive than a 272 cam. I also had the 268 cam that Rev noted, but thought I should've gone a step higher to the 272. I will say that it did idle well, which is one reason that I wasn't real happy with it.
