I'm not sure if this would work, or not, but what about another section, as well as the museum and M&MB, that people could add their own bikes, but in the year of manufacture.
For example, say if someone was building a race bike from 1983, and weren't building to factory spec, they could look in the 1983 section, to see what parts were around at that time.
Obviously, this would have a better chance of providing a good reference, if the members submitting bikes only added bikes with era correctness.