1988 Sea Ray boat 20ft 10"

I have a good used 26 ft Sea Ray boat has brand new shifter lever and cables recent oil change brand new distributor cap spark plugs plug wires motor was rebuilt 8 months ago starts up every time however I hear a slight noise in the right valve cover I was told that the valves need adjustment can let you see it and hear it run in my driveway, tags are still good on the boat until the end of September ready to take it to the lake $4,000 OBO