Good comment, the 7854 isn't wired up to do that. Maybe they used the pins for the readout interface or IEEE488 as on the 7B90P and 7A16P ? The digital section in the 11k plugin is probably not too difficult to hack, it's old school slow 5V logic and front panel controls could be added on, there seems to plenty of room. A pinout for the 11k vertical amplifiers would be nice but probably unobtainium.
Also, I just noticed that the 11A32 and 11A34 seem to built on a single PCB with the analog front and back ends connected via coax and the digital section stuck in the middle.