[Pete]

"For example the small diameter camshaft combined with equally small diameter lifters. Makes agressive cam grinds a little tough."

You really should gather more reliable information before making such statements...It has been shown in dynamic testing that the flathead Ford cam does NOT deflect enough when running to change the timing enough to record on a dyno..You can see absolutely NO deflection with a strobe while it is turning 7000 rpm on a test stand... It may be deflecting but you cannot see it...If you are familiar with strobe testing, you can easily see a deflection of .002...It is a commonly known fact that everything else in the engine will be worn out before the cam bearings....Deflection of the cam would show very early in worn cam bearings.
As far as lifter diameter goes, check the diameter of a Chevrolet V8 lifter and compare it to a flathead Ford lifter..Flat lifter Chevys will turn 8000.
Flathead Fords will turn that also on a test stand but guess which one will last longer due to much lighter valve train.
Plain old rocker arm engines such as the common V8 are a poor compromise as far as performance....They were built that way to sell many units and build CHEAP AS POSSIBLE.
In the past, desmodromic valve train was the hot thing as far as high performance went...F1 engines both in cars and motorcycles have always been on the leading edge of development and they both had that technology...When that became obsolete, electronic valve train was the new technology....No cam, NO ROCKER ARMS, no lifters, no push rods...Only valves.
GP engines nowdays turn 19000 rpm....they idle at 7000...
Rocker arms are Mickey Mouse as far as efficient technology goes.
Your mileage may vary.