Alright, managed to land a (relatively) inexpensive board off of ebay and my inexperience is definitely showing.  I figured it was pretty much slip the new board in, connect the edge connector and plug in the control connector and go.  It kind of worked; I have a board that plays and has sound but the controls don't work.
There is a bit of difference between the boards although they both are UMK3 Rev. 1.2.  There are 4 connectors on the same side as the edge connector, labeled P9, P10, P11, P12 w/ 7, 10, 15 and 15 pins, respectively.  The new board has the same things plus it has CN 3/4, EXT IN, Player 4 and Player 3 silkscreened on, as well.  The real difference I notice is that the #4 pin on both the P11 and P12 blocks on the old board are missing - it is present on both blocks on the new board.  I have a single connector that I plug into the P12 block on the old board and the controls work - plug it into the new board and they don't.
I swapped the sound chips from the new board to the old board and that didn't fix the sound issue.  So I'm thinking I should go w/ the new board.  What might I need to do to get the controls fixed?   So odd that just swapping the boards might mean rewiring things.   
