I am looking into building a LS3 non stroker natually aspirated for a 4th gen Monte SS. My goal is 600 Crank horse power or as close as I can come. I was leaning towards the Chevy performance heads https://www.summitracing.com/parts/nal-88958758 due to it seems like a good deal but my buddy sugested geting cores and having them custom built. I havent figured out the cam yet. what is everyone's suggestions on this? Are the Chevy heads good, would the custom route be the best way to go, or is there another brand that I should look at?