The 6x7 hinged Z-VI is a lovely, simple carrier for the TII, but it isn't necessary to make fine prints with. If you have any of the other larger neg carriers, you can just use those with, mat board (or such) masks. And if you're concerned about film flatness you can place other makes of 4x5 glass carriers, or just tape-hinged glass, over or in place of a larger Z-VI windowed carrier to work with just about any format 5x7 or less. Which is all to say that there are a lot of options if you fail to source the real thing.