Not to be pessimistic, but if you are set on pouring this mold with bismuth/tin, I would advise against it. First of all the keeper barely holds on when you use lead especially in the really small size. So in my opinion this is a task that I would not even think of doing. Second, that alloy is so hard, that you will either have really good success getting the jig out or you will fight with it trying not to destroy the jig head. In my experience, the latter is more common. If you get to the point of actually getting good heads, painting may be an issue. You can hand paint them without any problem, however using powder paint will be a challenge. Bismuth/tin has a very low melting point, and it will usually melt if you decide to try powder paint. However if you paint and bake way below the melting point, than you should be OK. Finally, if you use Drop-out for a mold release, it works great for lead, not so much for tin/bismuth. To me it seems that when tin/bismuth cools it expands a lot making it very tight in the cavity. Just and FYI but almost all the lead free jigs I pour are a b$$$h to get out of the cavity except for the round head jigs. I hope this helps some.
All said and done, if you want to go for it let us know your results, I'm curious.