Economical replacement rocker arm set?
It's difficult enough to check preload with the intake off, I can't imagine how much fun it would be with it on.
Not a fan of the non adjustable at all. Adjusting preload on used components is a pain in the ***.
With adjustable rockers, the preload is much more accurate and consistent, and, if a lifter or lobe goes bad you know exactly where to look for the problem.