Yeah, they're fine to be reused, so you could probably find one at the junker that's suitable.
I'm not a fan of combining RTV sealant with a gasket, but you could get away with this on the valve cover if you want to go ahead and re-use yours (if it's intact).
It could be that your valve cover is warped due to over-torque too. Take it off and check to see if it is flat and level. If it's warped, you'll never get a nice seal seal by replacing the gasket. Then, go find a nice flat valve cover at the junker.