clifford advertises the inline 6 stuff cause that is their nitche business, but they are the best place and the onlly place sometimes to get four cylinder parts. they made my camshaft and my entire valvetrain. my camshaft is more aggressive than any of the others i have seen on the market and at the time i did my motor built, they were the only ones that would even do the work. i called crane and lunati and all the cam companies and no one wanted to touch that motor
as for the stock parts, depends on how aggressive the cam is. my cam would destroy stock spings and locks. but if you are going with a cam that is not that aggressive you can get away with stock parts that are new as new will still be a strength increase over the worn stock parts that you have