For awhile now I kept hearing a ticking noise like a lifter.. Some days I can hear it and some days the engine ran quite. Today got louder and the engine lose power and not drivable.

I have not check around yet. Can the top half of these engine be rebuilt like doing a valve job on a standard pushrod engine?

Any suggestion where to start or what to start taking apart to narrow it down to what failed? Thank you in advance.