There is no hard and fast rule about sharing the same frame. Here is a discussion quoting BF's T-Mar on Centurion. The Ironman has 700c rims and early Lemans are 27".

http://sheldonbrown.com/centurion/

While brakes, cranks, derailleurs (oh forgot you are a SS guy), brake levers, saddles, and handlebars are usually transferable, you can run into difficulty on hub width, seat post diameter, stem diameter, headsets, bottom brackets, and shifters.

You might look for an early 1980's Trek or Schwinn Japan frame. Both are 27" wheels for the most part.