Kashmiri mirch is the color-first chili: deep red, aromatic, and comparatively gentle on heat. Most plain red chili powder or lal mirch is heat-first, so a 1:1 swap can make a dish hotter but less vividly red.
For a color-forward chili you can grind as needed, use Kashmiri Chili Peppers Whole. If what you want is a complete North Indian curry base rather than a single chili, use Rajasthani Curry Jar - Limited; just remember it is a masala blend, not a plain mirch substitute.