Rustoleum makes a high heat paint. There are 3 levels that offer protection at different temperatures. Here their website and information. I would contact them to see if this kind of paint will work for you. https://www.rustoleum.com/product-catalog/industrial-brands/high-performance/high-heat-coatings/high-heat-coatings
And here are two other sources of information that may help you!
Hi Harry: Check this site out: https://sarahjoyblog.com/how-to-paint-the-inside-of-a-fireplace/ Here is a nice forum to read before you make any decisions. Good luck
You can buy spray paint for high temperature uses, like to spray barbecue grills and fire pits. I like the Black shade made by Rustoleum.
Thank you for all your answers they will make it easier to make a good decision on what I can use .👍 Harry