That saved me a lot of time. I just ordered 20 of them made. When they come in I can send some out to those interested.
Actually count me out on those adapters, they will not work for the 1Fz. In looking at the adapters again, both the picture and the schematic shown on the arcade-projects link I can see that the MV-1B uses different plugs than the MV-1fz. It looks like SNK maybe ditched the KEL plugs (you can tell because they will say KEL on the right back side of the right angle plugs) for another brand and thus MV-1B's don't have the same problem of unavailable plugs as the 1Fz.
Here's a picture of the underside of a 1Fz if it was to be connected horizontally as we are trying to do. The pins are not only not mirrored like the pins on those 1B adapters, but the pin matching order is flipped on each set of 2 rows. I have labeled the pins how they match up verified with a multimeter.
Could you take a picture of the bottom of a MV-1B for me please? and if possible, could you measure the distance "X" with the 2 boards as close together as possible? I assume those boards on arcade-projects are already tested and working, but you might want to test how the pins match up on the MV-1B just in case.