It depends on the brake calipers. Some types of calipers have enough adjustment to just swap wheels. Since you have another bike with 700's, just try swapping the front wheel and see if the brakes have the adjustment range available.
The bigger problem will be on the rear wheel with the dropout spacing. A modern hub won't likely fit in the older rear dropouts without tweaking. A steel frame can be cold-spread to take a modern hub, by someone who knows what they are doing, but that would be something you would do as a one-time adjustment, you would not want to change that dropout spacing back and forth repeatedly, the frame could crack.
It would be worthwhile to build a set of 700c wheels for it to get the good availability of modern tires, and you can run a slightly larger tire than you could before.
wheel size
I have a fairly old Motobecane Grand Record (2nd frame replacing the origional that broke) that came with all Campy components, surprisingly including 27 1/8 inch rims.
As my other bike rolls on 700's, can I just put 700's on the Moto and adjust the brakepads so I can interchange wheels between the two?
"A steel frame can be cold-spread to take a modern hub, by someone who knows what they are doing, but that would be something you would do as a one-time adjustment, you would not want to change that dropout spacing back and forth repeatedly, the frame could crack."
Yeah, that scenario has me going back and forth as to whether I want to convert to a single speed or upgrade the wheel/cassette/rear-derailleur after spreading the frame on my Motobecane. My gut tells me that it simply isn't worth investing a lot of money in since the bottom bracket and tubing sizes are all very non-standard.
I agree with everything that edmonds said.