I would apply an acrylic or elastomeric topcoat. It is trowled on and wet brushed in tight areas. It comes in 5 gallon buckets similar to paints and you add the color of choice to the mix. If the existing topcoat is heavy textured, you will want to scrape or grind that down fairly flat for a workable surface. The acrylic or elastomeric topcoats you cant texture heavily, but you can light texture such as an "old world". It remains flexible and gives throughout the year with temperature changes and is bullet proof with little or no cracking. It's like having a rubber membrane on your walls! Here's a few links, we have STO on our build and are happy with it so far.

Here is a link that might be useful: Coatings