Missing Oil galley Plug

After a recent rebuild,I had trouble keeping the lifters adjusted, after being told to check the oil galley plugs I found one missing behind the timing cover.They are press in and i am not tearing it apart to tap them out.Anyway, the motor has about 1000-1200 miles on it.After replacing the plug, I cranked it over for about 15 seconds then re-adjusted the valves.They still have some noise, but it is better.I am going to let it run for 1-2 minutes, get the pressure up and re-adjust them again.If this does not solve the problem, is there a chance that driving it has hurt it and need a new cam/lifters kit.
By the way, 69/302 bored .030, WP heads(190/164), Comp Cam(523/520 lift),Edelbrock Air Gap, 600 Holley, Hooker Headers and Flowmasters,C4 with 2500 stahl and 355 gears.

If the lifters were starved for oil during the last few hundred miles it might already be too late...

Did the plug come out after the break in or during etc...

Is the cam broken in properly?

Is the noise coming from a bad cam/lifter problem where they are slowly wiping each other out thus making it necessary to re adjust the valves?

OR, are you just doing the valve adjustment wrong and leaving too much room?

I do not know if the plug was missing or if it came out. I have adjusted the valves according to comp cam instructions.Exhaust almost up,adjust the intake, intake up and almost back down, adjust the exhaust.Same procedure I used on my car and everything is fine.
I did start the car once with the valve covers off and they all shot oil out past trhe fenders.

that means the oil pump is working

I don't think you're going to hurt anything unless the valve noise comes back worse or get's louder.

If it get's worse then something is either wearing away or your nuts are backing off...