The main difference is that I was able to find an edge connector with card guides that the Nixie module can plug into, so the module didn't have to be soldered in place. It's not an exact match: the connector has a 0.156" pin spacing instead of the module's uncommon 0.15", and the width between the card guides is slightly greater than that of the module. However, with thin plastic shims glued into each guide, the module reliably fits the connector. The cumulative difference between the module and connector pin spacings means that the contacts don't quite line up, but even the outermost ones still have 50% overlap between the two parts.

Also, I used a different style of power transformer, one thin enough to mount underneath the Nixies instead of above. That makes this clock much less top-heavy than #1, which is a more important consideration with this clock due to its swivel mount.