How about this and a tune? (Fits other LS with 4.00+ bore...):
LS3 CNC-PORTED HEADS & CAM KIT
P/N 19300535 / MSRP: $1756.25?
If you want a little more out of your LS3 engine, meet this dynamic duo of CNC-ported heads and high-lift camshaft. This kit pair can increase the power of the LS3 engine in your Corvette to 470-plus hp and 440 lb-ft of torque. Developed by Chevrolet Performance engineers as a direct replacement for the factory-installed heads and camshaft (tuning required), with 276 cc intake runners and 2.165-inch/1.590-inch valves.
The camshaft makes the most of the heads? generous airflow attributes, with .591-inch/.591-inch lift and 211?/230? duration at .05 inch and a 121? lobe separation angle. This kit fits other LS-family engines with at least 4-inch bores. Contents include the camshaft and fully assembled cylinder heads. Head gaskets (P/N 12610046) and cylinder head bolts (P/N 1780056 must be purchased separately.