1971 Roadrunner with Midland-Ross Brake booster, power drum brakes originally and automatic transmission with 3 speed column shift originally.

Can anyone identify this hole to the right of the brake booster between it and the hood hinge? It seems as if there was a repair made to the sheet metal and they only covered up half the hole. I've never been able to identify what the hole was used for originally or if it just came from the factory with a plug and the plug was lost.