I had plans once to use a '60-'61 Rambler American insert, cut in two and the pieces on end and ****ed 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.