If you could find some the right size. Problem is adjusting them is a pain. With an adjust able rocker you just remove the valve cover, fire it up and adjust until the rattle goes away or the valve starts floating.
this is what i know: if you use hydraulic lifters you adjust the preload, alternatively you can use proper length pushrods if you don't have the ability to adjust the rockers or pushrods. if you use mechanical lifters then you adjust backlash (if you preload these the valve will be open).
if a hydraulic lifter is damaged and not holding pressure (bleeds right away) then it should be replaced, adjusting the pushrods or rockers (to quiet down that lifter) can cause the valve to remain open
