Yes, point taken it was a bit broad of a question, rather than specifically is X derailleur appropriate for Y frame/ time period etc. It was more impatience and tiredness (was up past my bedtime ) than laziness. Not quite sure the task is 'Enormous' either (But it's best not to go there with the misappropriation of words thing again ) bikes have had a pretty slow evolution between end of WWII and start of the 90's so some slow and steady reading as prescribed by Dr. Bandera ( I sincerely jest) should get me there.