At my talent level, sounds like I'm best to simply get a new single master - re-connect to the current hydrovac (which is working fine) - and re-kit with new lines, slaves, etc. for a "new" system throughout minus the Bendix, and hope for the best.
What are you other heavy big bolters doing out there? Is it either all in with crazy amounts of time and $$ to retrofit in a newer brake system on the truck or are there any other simple solutions? I'll try to get under there and see what my Hydrovac #'s are at some point today. It does look like a vac that has been replaced not too long ago. So...