My 440 source headed 505 has a hydraulic roller about the same size as Andys. Used Isky 8005A valve springs and haven't noticed any valve float up to 6,000 RPM. I have the rev-limiter set at 6,000 so I never ran it past that, but it does rev really fast and easy to 6,000? The Trick flow 240 headed 505 we are building for a friend, has a slightly larger 242 @ 0.050" solid roller, and using the solid roller valve spring / Ti retainer version of the Trick Flow heads. Right now the car that engine is going into has no rev-limiter, so it may "accidently" see over 6,000 RPM?