Saw a post on the Chevelle site of a guy who makes aluminum spoilers for Chevelles. They're really similar to the first gen Camaro ones, and come painted flat black. I went ahead and ordered one for my 64, just installed it today. Had to get creative with the mounting as my intercooler eliminates the lower radiator support mounting holes in the middle, so I did some cutting to make it mount to the bottom of my intercooler support bracket.
I like it, not sure I'll keep it on there, but it does add something to the front end. Going to wait and see how I feel after having it on there for a while.