I think its perfectly possible that you can use a Wizard Bonded Item and the Bladebound archetype of the Magus, because the Bonded item is not a familiar, and does not counts as one and the Bladebound archetype only forbids you a familiar, not a bonded item.
I would say no. If you are bound to a Black blade, you can not bind to anything else. Not a familliar, not an arcane bond. I would however allow a multi-class of this type to use the blackblade to get the 1 spell/day an arcane bond object would give you.