Seems I have been away for too long...
sorry...
A few notes on Egli frames: The backbone design of Egli was copied by a number of other framemakers, but it was (almost) never licensed by Egli. There was no need to get a license from Egli - Fritz Egli had "borrowed" the principle from Vincent himself. (There was a company in either France or th U.K. who was licensed by Egli to produce genuine Eglis back in the 1970s or 1980).
Similar frames were produced by Georges Martin, Manfred Rau, Gilbert Chatelard, Luigi Segoni, just to name a few.
Genuine Egli frames have a frame number that starts with "EVH750" - Egli Vincent Honda 750.
Hope that helps to get you started - if you need more information or have more questions, just let me know.
Axl the Satanic Mechanic