Hello, I need some help please. I have a stock 272 motor that was running great ...until I messed it up. Went to correct a leak on my valve cover and in my haste I installed the valve cover upside down ( aftermarket..no script)  
Started the motor and immediately heard the rockers hitting the cover. This result in dropping a push rod. Push rod was not bent and I got it tack in place. But the motor runs extremely rough. missing backfire etc. I checked that valve lash and everything is at .016".  

So my question is what should I check next?  Seems like the timing is off. I tried to adjust that but no fix yet.  

What damage is possible from the rockers hitting the covers?

I appreciate any advise


thank you

Bryan