If your tappets are truly ticking then a valve adjustment may not make the noise go away. I would definitely make the adjustment and retest. If the noise persists do not ride it.
A very high wear component on these oldies is the cam follower bearings. These were updated in 2003 for a good reason. You don't want ground up needle bearings dispersed throughout your engine. Check your oil screen for shiny chrome bits. Sometimes a loose timing chain can sound like the tappets as it contacts the cylinder. Check your cam chain adjuster and see how worn your timing chain is.