I still would want to see it rev to 8500. The spring pressure needed to control the valve train would probably collapse the lifter.

How far do you think 300 lbs springs would get you as far as rpm goes with a standard valve train ? Look in the catalogs and see what kind of springs Crane recommends for their race cams at over 6000 and you'll see the difference (and let us be honest at over 6000 you are not talking about a standard engine anymore). I don't say you cannot go over 6000 but their is definatly a risk of valve float. When piston to valve clearance is close (as with most high lift/fast/long duration cams) you could end up with the pistons hitting the valves once floating them. I suggest you also take a look at the lift those hydr. rollers use. Ultimatly i don't think they produce enough lift (in fact it is airflow through the heads) to accomodate any 350+ ci V8 to go to 8000. Do you for instance know what engine they used to go to 8000 with that cam ? When looking at cam specs, you need to look at the engine in which it is going also.
Plus there is also the aspect of valve bounce to consider. Once major intesity is high enough to produce a good power cam, you run into the risk of valve bounce, thus the need for stronger springs. If you have a high lift cam and a certain open duration, you will automatically increase the major intensity of the cam. Alternatively you could reduce lift, reduce intensity but increase open duration with all of its negative results.