Lifter Ticking

Thinking about replacing all the lifters and having the pushrods checked. How would I tell if a cam lobe was damaged/worn. I put a vacuum gauge on and I'm at 20lbs. Also talked to the guy who built the engine a couple years ago and he said the heads were, 360 big valve heads #3769974 with adjustable rockers, there's only abot 1500 miles on the engine.