1979 Chevy Camaro Problems after replacing intake manifold

Engine Mechanical problem
1979 Chevy Camaro V8 Two Wheel Drive Automatic 137k miles

hello,

I recently took my car to have the intake manifiold gaskets and the valve cover gasket replaced. First I noticed the timing was wrong after I left the shop. Brought it back and they "fix it ". Next day I checked the vacuum hoses to see if they left them like the vacuum diagrams by the radiator and nope. I put them back the way they were and the timing changed again. Someone helped me and moved the timing just I can drive it back to work and take a closer look. After rearranging the hoses again, set at at the right timing I still cant get the right air/fuel mixture in my carburator to the point to adjust the carb to get me 1000 RPms on idle so the car wont die when I put it in gear. A friend told me that he noticed a knocking sound at the valve covers and yes appears that they bent one of the covers and now the rocker arm is hitting the valve cover.
Do you think this is probably the cause of why I can't get the right mixture on the carb since the valve is not opening all the way up?

Any input will be greatly appreciated it.

Thanks!