Thanks, guys.

I'm hoping that with the extra .060" taken from the valve installed-height from using the CC spring locator shims, that I can squeeze another couple of hundred revs out of it.
I have been considering the Crane Sportsman shaft rockers for a while. At $959 (with the $ at 1.6 to the £) they are starting to look more affordable. Anyone have any experience of these? Apparently they use a special polymer-matrix composite bearing instead of needle rollers. Maybe they would help a little bit with the heavy valvetrain inertia?? At the moment I am using roller-tip Comp Cams Magnums (not full-roller Pro Magnums). Another good thing about the shaft rockers is that I think I can get away with the stock valve-covers, because there is no big poly-lock sticking up in the middle like there is with a stud-mounted rocker.