700c and 27 inch

It's undesireable for two reasons:

1. A big gap between the tyre and the frame just doesn't look right. I looks like the frame wasn't designed to take those wheels (it wasn't)
   
2. Long reach brakes are more prone to juddering.
   Braze on cantilevers solve the juddering problem. If you can't get brazing done, an alternative is to use Resilion cantilevers which bolt onto the frame. These are antique, and you won't be able to get the 'split' cables they need, but that doesn't matter because you can use a mafac centre pull type hook and a straddle wire with a solderless nipple on one side. All you've got to do then is to figure out a way of making some suitable brake blocks!
   
   

I have an Alhonga brake on one of my bikes (using 700c but designed for 27"). Granted, it looks worse than a steaming pile of poo, but I can't recall it ever juddering and stopping power is better than my other bike which runs a short drop 105 and Crosstop lever. Same rims on both.

But the Alhonga's do nothing for the aesthetics of the bike, nor does the large gap between tyre and fork crown :(