I used Bon Ami to clean the mirrors in an arc lamp used for professional projectors in a theater in the 50's and 60's. Would this do to polish and clean Graflex (Heiland) flash reflectors?

If they're chrome plated, you could try 400 or 600 grit wet/dry sandpaper, used wet. I recently restored to like new the appearance of chrome on a Raleigh bicycle. I've even polished plastic watch crystals this way and it works! You can do a final polish with toothpaste (I prefer Colgate for the taste).