78'280z'er

Yeah, I think either way need to at least pull the head and check things out... Anybody have any recommendations for a good shop for Z cars in phoenix area ?

In the past I’ve never experienced any mechanical issues with this engine, just done regular maintenance, some upgrades. Unfortunately car has not been driven for close to a year. Last time I drove it before it run fine. Couple months ago I finally started it only to find out it was running extremely rough, w lack of power in first couple gears… Today I finally pulled the valve cover off just to find out the rocker slipped of the valve. Then I noticed the two parts floating around… Maybe the pictures will explain better: How would I go about putting everything back? Do I need to be concerned about why this happened ? Any advise would be great, thx in advance.