cam help

Good day everybody !!!
Question? On the same subject I just picked up a super six setup for my /6. I would like to just increase the power enough to equal the addition of the super six setup (hope that makes sense) What cam could I use? A little more torque,hp, and still save gas. I plan on making my duster a daily driver. The Trans is a stock 3 spd. One more question. Can I exchange the cam without pulling out the motor or taking it apart?

Thanks,
562bigdaddy !!!