Sorry for the big interval since my last post.
I've ordered 3 more VBI Injector boards from OSHPark.com and they should be here this week (or next week). I will then send two of them out to testers who are able to further test MACH 3 and test Cliff Hanger. Warren also has ordered a PCB from OSHPark.com to help him power his MACH 3 boardset so he will be testing that game soon too.
In the mean time, I've been digging into the Star Rider schematics, specifically the PIF board, to try to understand when it lowers the PR-8210A's "JUMP TRIGGER" line relative to VSYNC. I've pretty much decoded the entire schematic for the PIF board and documented the memory map. I'm kinda getting derailed from moving forward making a rev3 Dexter board though, so I think I won't keep continuing down this path until after the rev3 boards are made. I think I know enough about how Star Rider uses the PR-8210A to have the board made without the software being written.