you can try 3.0 cams but the gains are not going to be worth the time. i'm not sure what you have got, but aftermarket cams are not really worth the gains for anything near a stock motor.
i got a question...i belive the cams have a lot to do w/ the rpms @ which the peak power is produced. so wouldnt the timing have to be modified and wouldnt u need to use a different grade of fuel? i mean usually aftermarket cams let the cycles go on a bit longer...
timing fuel management and quite a few other things are gonna need to be changed or at least slightly modified to handle that. we all know what cams do so yes the cycles do go on longer and if you arent going to change the fuel and timing it wont help much at all. but it will help a little just not much and not worth the time like downer said. but if you did all that the gains would be better.