As Lou said, you really need the PS32 board with the 5V connectors, then you can just replace the board without changing any wiring. It is a tight fit in the tender, but since the full upgrade kit PS32 board is the same size, that problem doesn't go away with the full upgrade.
I also still have a few of the older 5V PS/2 boards. If my Climax board ever croaks, this is one place that I may consider just dropping that board in.