There is no reason to replace the stock heads that you already have. My buddies friend has a EX cab silverado with a 5.3. He's done new pistons, cam, procharger, and bought a very expensive set of Ligenfelter 6.0 ported heads. He actually lost power when he installed the heads (Long story short he burned up the number 7 piston orginally with the supercharger) So he put back on the stock 5.3 heads and is making a hair over 500 rwhp.

As far as a good supercharger cam goes the 212/218 high lift on a 114 lobe.