The bolt grommets are available from Rock Auto, eBay, Napa, etc. but you might just as well replace the other valve cover gaskets. too. Get a quality valve cover kit and avoid the cheap ones - they don't last.

Check the hose from the top rear of the valve cover to the air cleaner, and the hose from the carburetor base to the PVC valve. Make sure they're clear and clean. Also check the PVC valve. It should rattle. If it doesn't, clean or replace it. That should help deal with the blow-by effects.