Camshaft i will be using is a comp cam 290HR-12..lift is in at .510/.544. Ive been looking for a set of single springs since ive been told for a duel design spring..the head needs machining? If need be i will go the duel spring design path. Just looking for suggestions here..what are my options? I wouldn't mind hearing some opinions on the rest of the valvetrain either...locks, retainers and pushrods as well..