I think it depends on the derailleur. Old recor geometry not likely... no Victory, triomphe, C-record, super record etc... CHorus and Athena? Maybe, but they did change quite a bit when they went to 8. Try it and let us know. Assuming you already have the parts to try it.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear