i recently changed the oil in my gta,i went from fully synthetic to a convential oil,i also put in a quart of lucas,now it sounds like the lifters are not pumping,there is a clicking sound on both sides of the motor,but my oil pressure is 60+ pounds,i also put the short oil filter on that has the anti drain back valve on it,what do i need to do to prevent any engine damage,also the car sat in a field for 6 years,can someone please help me.

 

If you have 60+ PSI of oil pressure your pump must be working..
I don't know about the oil filter itself, Even with shorty headers I can still use the one suggested by GM.
Sounds like your rockers are out of adjustment.