Dan: If I may ask a question, what pressures are Eureka's safety valves currently set for?
Glenbrook is a close relative of Eureka as both share the same internal boiler dimensions and many of the same basic components (dome, sand box, cab dimensions, etc are all the same). Essentially they're the same locomotive from the waist up, except Glenbrook has more muted ornamentation (less brass, painted cab, etc) befitting a freight locomotive. They ought to look brilliant together.
Last I read--many years ago--Glenbrook was to be rebuilt to original condition. Hence it'd have link couplers and no air brakes. From what I understood that was one of the major attractions of potentially double-heading with Eureka, as the latter locomotive could provide the modern coupler and air. Is original condition still the goal of restoration?