Wang 300 Calc

I received two orphan 320K keyboard/display units a few years ago (no logic unit). Hobbled up a little level-shifting hardware and wrote some calculator code to drive them from a SWTPC 6800 - in other words the 6800 was replacing the missing logic unit. Worked fine but the next (intended) step was to redo it all in a microcontroller and stuff it inside the 320K case so it would be a stand-alone 'modern' nixie desktop calculator. Would be kinda nice because the 320K KDUs have a small footprint compared to other nixie desktop calcs. There is very little spare room in the case however. I think I anticipated it would be feasible if one used an external wal-wart (ugly) for the power transformer. The KDUs are very well built: cast aluminum case, micro-switches for the keys...