Stop in for a cup of coffee

FISHYPETE said
The hole is to be oval shaped, would a type of grinder work to hone it out?

Yes, thats what I would use, remember to tape it up, will help to keep it from chipping, Toolman has the right idea, use a stone on it and don't get in a hurry, I removed my antenna hole off my 66 Valiant passenger side fender