Valve 318 question

The tic - does it go away at higher rpms? if so it could be a lazy lifter, but since you changed the cam, I presume they are new lifters? Could also be worn or slightly bent pushrod or worn rocker arm (or both cumulatively) I assume you checked rocker shaft hold down torque?.

Does it get better when the engine is warmed up rather than cold? If so, could be headers ticking against the head. Are you running old style steel shim gaskets or a thick composite header gasket (they appear really thin in the picture)?