I mounted some spare XTR v-brakes onto the magura mounts on my Nimbus Nomad 29"; they work fine. I didn’t buy special mounts, just basically used the technique from this thread. I did add a brake booster, since the magura mounts aren’t too sturdy if you are just using one hole on each side.
They have more than enough power for Muni use, and more tire clearance than the frame does (I’m using a 2.4" Ardent tire). Not sure if they would have the needed clearance on a 24x3" tire.