26" to 27.5" wheel swap?

[eightyeight]

Triggers broom theory is how i circumvent my promise of not buying a new bike although my mrs now considers a frame a new bike

 

[chambo34]

Oh and incase anyone else is reading this for advice, don't do it with suspension forks. A heavy impact on the front can lead to the tyre hitting the crown, jamming the wheel and sending you flying.

its a fully rigid frame, rides surprisingly well for a non descript frame.

 

[novocaine]

I don't think you'll manage it with that frame, the clearance to the chainstay bridge is to tight as is the separation between the stays.
all I can suggest is find someone with a 650b and borrow a wheel.
As to rim brake options, not many out there, you'll be on very much budget rims or worse, road rims .