best cylinder head

So my 340 seems to run out of steam right around 6700 rpm. Cam card states op range of 4500-7500 and my specs are 340 with 11.7-1 custom ross pistons forged, 302,309 duration .654/.655 lift solid roller comp cams cam, X heads with 2.02 valves, harland sharp 1.5 ratio rockers, super victor intake with a 750 berry grant carb on top. Any suggestions on the best heads i could run on this? seems to be what wipuld be holding it back the most