I'm assuming the Ardesa pistol you are intending to buy is a single shot. If so, then the mold might be a good one to try if you can find out the actual bore diameter of the pistol. Minies need to be smaller than bore size by a few thousandths of an inch. This one at .450 might make loading it into a .450 bore problematic unless the bore was absolutely squeaky clean.There are any number of other styles of bullets designed to be used without a patch, some which are supposed to be engraved with the rifling as you load, meaning they are a little over bore size, so maybe if those work, this one would, too. I bet it would shoot very, very well once loaded, also.
I can't tell what the mold costs and even if I could, I have no notion how much that would be in USD. If it isn't TOO expensive, I would buy it if I was in your position, but I also have sizing dies in .446, .447, .448 and .449, so I'm confident I could make it work for me. I'm kind of a mold junkie, though, kind of like that Marcos dame was with shoes, so my advice is probably tainted.