I was able to get in touch with Bob and he provided the answers I was looking for. In case anyone is interested, here are the steps to convert an AC UCUB board to DC:
•swap out the two jumpers from the underside of the board with a bridge rectifier (orientation is silkscreened on the board)
•remove the green motor field wire from “D” and jump the black wire from “C” to “D” (yellow & blue motor brush wires are soldered to “A” & “B”)
And that’s it.
Thanks again for your help!
Dan