I'll give that last option a shot and see what turns up...

the TI chips are SN74BCT2420FN "Nubus Address/Data Transceivers And Registers"

http://pdf1.alldatasheet.com/datasheet-pdf/view/130241/TI/SN74BCT2420FN/+031_5_VRh/1yOvNGH/1vwCvP/1+/datasheet.pdf

I'll try to get better pics of the board- also, I've got some better adapters for my chip programmer so I might be able to dump the eprom (assuming UV hasn't wiped it)