xodaraP
Enlightened
There are additional chips piggybacked on top as well but I'm assuming those are the same type of logic with additional IO channels.I wouldn't mind sharing the info but I don't have a Gunforce board handy to give proper details.It shouldn't be too hard to run wires for the missing address lines though, just by comparing with an other romboard.I guess your best option is to follow the picture above. I don't think those who can do this are going to release the information publicly.
I have a Gunforce handy, if you're happy to document the process I can ship it to you or take some detailed photos