Never had a problem with old bike barn... very reliable, but I also use bike bandit, normally cheaper than OBB, although they do not carry as many OEM parts for my model 77 CB750F2, as does old bike barn.
I also use a place in Cincinnati, it is a Honda dealer but has a separate parts department for Vintage Honda Parts! (Western Hills Honda, Cincinnati Ohio), But my favorite is a motorcycle junk yard right down the street from me, it has tons of old Honda's all over the place.