In the past lots of brands used to share one frame over a few models, Bianchi and Cannondale most easily come to my mind. I believe Schwinn did it a lot too and though I am unfamiliar with them I think trek did as well.
I think in your case you need to concentrate on just making sure your looking for a full chromoly steel frame and fork and it is built for 27" wheels.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk