Painting brick fireplace

Free? Is it safe to assume you intend to pay for the paint & tools?

You might strip and acid wash first, see what you have, a color that matches Limestone Is Benjamin Moore Briar Wood mixed with white it will look like any Lime Stone shade.

There are high-temperature paints. Look for BBQ paint. Personally, I'd prefer no paint at all.

Maybe fireplace stores and paint specialty stores would be places to ask for referrals.

We did a similar process in our old house. The brick fireplace was just as ugly as you describe. However, we did bring in a lady who was an expert in the field to do the real work. She not only did a faux-style paint job, she had a mixture that contained some sort of silicon sand or something, so the final result looked like sandstone, complete with texture and "sparkle".

It wasn't free, but her work was fairly priced, judged by the result. We figured we'd be looking at it every day, so cheap wasn't our main priority.

I'd check around and ask to see some portfolios. At best you'll find someone who can do the job reasonably priced. At worst, you'll see what you want your end result to look like.

Cheers