[Keithc8]

Not enough information to give a good suggestion. Just get a steel core and be done with it. I can not see any of the springs controlling the valves at 8000 rpms unless that is one really smooth low lift camshft. If that is the case it will not make power anywhere close to that so why turn it that high. If I had shaft rockers and wanted to turn 8000 rpms I would get a better camshaft where I could run at least 200 to 220 on the seat and about 600lbs open. Do this all the time on circle track dirt cars and run them all year long. Just depends on the power you want and what you plan on doing with the engine.

Good luck, Keith