So what am I looking at exactly

I decided to take off my valve covers and clean them up and give them a fresh coat of paint. I was expecting to see stock parts under the valve covers but found adjustable rockers. I don't know any history of the engine other than it is the matching 340 that came in my car. Is there anything I can assume has been done to the engine without tearing it down. Do adjustable rockers mean I have a solid lifter cam? IMG_3395[1].JPG IMG_3397[2].JPG