Most online Honda parts vendors have the online micro-fische that you can find the factory part number...
SOME have a reverse parts look-up, in other words you enter the part number you have and see if it is available...
Of those, some like
www.hondapartsnation.com have the applications "Where used" button that you can see all what bikes had that part number installed.
81 Honda CB750C - Current Project
67 BSA Spitfire MkIII - Next Up (Full Resto)
81 Honda GL1100 - Bob / CafeĀ“
80 Suzuki GS750L - Bratstyle
72 Honda CB450K5 - Basket Case
73 Honda CB350F Cafe' (Gone but not forgotten)
Don't wait for opportunity to knock... kick the door down and drag the old harlot in!