What is recommended as far as valvetrain parts for a 12v turning from 4800-5300rpm? I am only curious about valve springs and aftermarket valves as I have the titanium retainers, hardened keepers, HD pushrods, and billet cam. Are the 60lb valve springs from Scheid holding up pretty well??? Are there any problems with running the stock valves or is something much better needed? Are roller rockers needed? Thankyou for any feedback.