Originally Posted by halfspeed
You can probably upgrade to modern rims, but you'll need to rebuild the wheel. My '80's 620 has 700c wheels now. The brake reach on the stock cantis worked fine.
Honestly, if the wheels are in good shape there's no reason you can't stick with the 27" ones.
Are decent tires easy to come by in this size? If so then I may stick with the size. My concern was getting tires and tubes for it.