Fix the exhaust leak first. They can sound like a tapping. Since they are synchronous to valve operation, you get the gist.
I usually pull the entire exhaust manifold, spray all surfaces with copper RTV, and reassemble. That always silences exhausts for me.
Also, since it is a 2V (though it should have the updated heads with more threads) a loose plug will also tick.
OP: These engines really don't have "lifters" being OHC. They have roller followers with HLA's that just take up the slack on the back side of the rocker assembly to keep tension on the lobe/roller/valve interface. Yes, they will allow a tick to occur if they stick however that's relatively uncommon and usually a noise on these engines is from the exhaust, which are notorious for leaking at the head/manifold interface, or a loose plug, which is more common on the earlier 3-thread engines.