Aluminum heads whos the best?

Well, CNC can be done any time, and the associated work will also mean a spring and cam change. Rather than buy the heads with the expectation of growing the engine into them later, I'd rather build for what you need now, and leave the option to go bigger later as you feel like it. The other issue is with Cometics, both the block and head must be finished ultra smooth. The factory finish on RPMs is boarderline too rough for them.