Thanks for mentioning the arch differences, I knew that at one time. That makes me happier. I think the brake is plenty wide enough for 32mm tires at the standard spacing. I'm not sure bigger would be a good idea, maybe 35mm? Spokes aren't what they once were, I have had some weird failures in the last year, so I'm worried about clearance with a broken spoke. In fact, the wheel I have been using for fit checks has a broken spoke,so I can easily test

This frame was built for 28mm with fenders, but since it never got chainstays, I can make it fit 32mm. TT might tilt up a little, but I'm assured nobody cares about that anymore.