Hi Ray, I am surprised you chose brass for rockers? I should have chosen steel of a good grade? I am sure you are aware (but others may not be so?) that the rockers take extreme repeated bending and as a crystaline material are more prone to fatigue cracking than wrought materials - (I think? - Any metalurgists to help here?). So I should have used a fatigue resistant steel. I know many cars, trucks, etc. appear to have cast rockers, but they undergo lots of fatigue testing to prove the design. I am sure your engine will not need to last as long (many 1000s of hours!), so will probably be OK, but I simply believe the best material should be used where practical on models. - Mostly they outlast us!
Also, will you be lightening the "arms" of the rockers to H-sections? - removing "redundant" mass? The mass that is oscillating in the valve train causes power losses and wear of cams and followers, so minimum mass should be attained where possible. More mass means heavier springs are needed to permit higher revs, etc. before "bounce" occurs, so should be carefully minimised.
When proving tests were done at the factory where I worked, we built rigs for 1000hour idling tests, as that was the test mode to develop maximum cam and follower wear. (due to lubrication and loading of the cam to follower interface). But fatigue tests were at maximum revs for a couple of thousand hours and cycling from idle to max, holding for long periods at certain "resonant" speeds! Rockers were wrought steel from a SOH Camshaft. (post 1990 engines had DOHC with bucket and shim cam followers. - MUCH more durable than rockers.).
If anyone can correct my thinking on "materials", I should like to learn more from your expertise.