Both posts can be addressed here.
Valve train noise can be notoriously difficult to identify and/or correct. Having said that, things to check are rocker cover clearance around the valve spring retainers, push rod rub at the top of the covers, valve/piston clearance when using oversized valves and/or thin head gaskets, valve spring to guide seal clearance when using high lift cams, cam lobe to case clearance with high lift cams and 04E cases, tappet to case clearance with high lift cams and rocker to valve collar clearance (rare). Of course, these are all things that should be checked during assembly. Since neither of these are gear drive cams, we'll skip that discussion.
Another noise source can be the valve springs themselves. Dual coil valve spring sets can have a harmonic or surge that can manifest as valve train noise, typically around 2800-3200 rpms. This is often impossible to elemenate because it is a function of the spring design and its applicataion. This has NOT been known to cause failures but is chalked up to a price we pay for the performance. Our LMR-002 oil bypass spring was designed to help address these issues.
Roller rockers were mentioned as a possible solution. We've not seen rollers help and in fact may increase the noise.
For Jeff, the HPI 55 is not a bad choice and I would have recommended the 57 with ported heads. The good news is that on EFI bikes, size is less of an issue and it's better to be too big rather than too small (people are still thinking carburetors, see Kuryakins' note on this). Curious about the "2cc off the flat tops". Was this done for clearancing? It would seem this would lower compression, but I may not be understanding just what was done.