I had plans once to use a '60-'61 Rambler American insert, cut in two and the pieces on end and butted in the middle, with some kind of piece of skinny stainless down the middle to hide where the two pieces came together. It's just aluminum in a pattern of regtangles. One grille was free and I paid $20 for another one, later.
Used some expanded steel and painted it, kept tabs at side to bend and rivited to existing holes in radiator shroud.