Chris,
They fit my Cheviot with Paul Racers just fine on A23 rims. Probably could've done SKS fenders by cutting them up so they don't go under the brake arms. Brake clearance was more of an issue with the Tektro 559's.
Currently also have SBH's on my BDB Pelican on Synergy Rims. They measure at 44.5mm. the BDB Pelican has the Grand Bois fork crown which is 53mm, and I believe the earlier Ramblers use the Pacenti PBP crown which is 56.5mm clearance.
I'm going to mount them up to my Pacenti Brevet Rims and I'll take measurements later tonight. My custom is also coming within the next couple of weeks, and using the Pacenti PBP crown and Paul racers. I can see if they will fit under the fenders then.