Yeah, finest kind maxing out the Predator on stock valve springs, as long as you wish, valve float will prevent excessive rpm's. NOW HEAR THIS: Don't even consider replacing the stock springs with heavier springs unless you first replace the flywheel! PVL racing flywheels are only about $70, and tested at 17K rpm's. If you take your stock cast iron flywheel past the 5200 rpm valve float point with some heavier springs, you run the very real risk that the cast iron may explode. At say 6K rpm, pieces of cast iron can pass through your skull like it was made of cardboard. While you have the flywheel off, the pin the governor gear spins on is exposed. There's your chance to just punch it into the block, instead of fighting for it from the other side. Be sure to remove all those internal parts laying in the block, and the governor arm hanging down from the top. Put 1/4"-20 bolts in the holes.