the usual 21mm for H03 has the single on always on top side
the ones with on down side originate from C8F 21700 design and have it always in that position, but other sizes can be differnt
First, you would need to swap in a new driver that was already setup with NarsilM. That’s pretty easy. The potential hard parts with the MF01 is if it’s not an early unit, it will probably be glued shut and very difficult to open. Secondly, the emitters will probably be set up at the wrong voltage requiring you to cut traces on the led board (mcpcb) and add jumper wires.
I would start by seeing if you can get the front bezel off your light.
You don’t list your location, but if your in Europe you might be able to ship it to Lexel for a conversion. Outside of Europe the shipping costs go way up.
BTW, do you know about the new MF01S It would be way cheaper to sell your current one and buy the new one since it already comes with many improvements. No NarsilM, but Anduril is based from it with nice ramping and user adjustable features.