Ticking sound, Help please

-Thats not a tick; its a clack. And clacks are almost always rocker-arms. Could be lash, or stud, or other interference, or a breather.To me it sounds like a typical old style GM small block in need of a valve adjustment. Those arms have a rather unique sound.
-Sometimes a fuel pump arm will clack if the return spring isnt doing its job, but its in a different location.
-And sometimes; just because you can do something, doesnt mean you should.
-Exhaust valve clatter can be heard really well in the header-pipes using a long 3/8drive extension stuck in your ear; intakes,with it sitting on the intake runners.Practically impossible to miss-diagnose.
-Good luck.