I have access to a Dearmond, an MIK-NS and a late 90s (MIA) Guild Westerly which I can reference.
I just measured a couple of aspects of the "Barrel" bridges on a DeArmond SF and on a Guild Westerly SF (late 90s reissue). The outside end of the "E" barrel to the outside end of the "G" barrel measures right around 2-3/4" on both. This is with all barrels snugged together, end-to-end. The string spacing is is quite similar (not more than 1mm difference, if that.
Though the overall shape of the BB ("Barrel Bridge") base plate and that of the WSB ("Wood Saddle Bridge" [as found on the MIK "Newark Street" reissues]) is very similar, the BB is slightly wider (not a big deal). However, the bridge plate mounting holes do not match up (a big deal for those who don't want to drill extra holes in the top.
Knowing Guilds history of "using up" stocks of parts from discontinued models on current offerings, I'd guess that the BBs used on DeArmond Starfires were left over from Westerly Guild Starfire production. Somebody please correct me if I'm wrong, but I think DeArmond SF production began (or at least continued) after Westerly SF production had ceased and they stopped making the DeArmonds before they started production of the NS SFs.