Maillard used the same standard as Suntour on their 2-notch freewheels, so a Park FR-2 or equivalent will work fine. The EXTREMELY key thing with using one of these though is the proper securing of it to the freewheel before trying to force it. 2-notch freewheels are infamous for stripping or breaking either themselves or the tool during removal. (That's why Suntour switched to 4-notch, and Maillard switched to splined after a few years.) Make sure the tool is perfectly engaged with the notches, centered, and snuggly held in place by an axle nut or quick-release skewer to prevent it from shifting out of place when spun. I find that clamping it in a bench vise (so the wheel is horizontal) and using both sides of the rim/tire for leverage is safer and more successful than just pushing on a wrench. Spraying some penetrating oil at the junction between the hub and freewheel body beforehand can be a good idea too. Once you've loosened it slightly - like a quarter turn - you can remove the nut/QR and spin it the rest of the way off.