Unfortunately I'm not sufficiently into such matters that I understand what 'the old JP
's' are or what 'OAG's' are! Apologies for my ignorance.
Let me give you an example.
In many cases I have all but the aircraft make/type. For example -
Iberia IB5151 Heathrow to Bilbao on April 26 1995.
British Airways BA485 Bilbao to Heathrow on April 28 1995.
Perhaps I am expecting too much to expect to identify the aircraft make and type after such a time lapse!