You still have the stock exhaust system?
The 069A carbs will work with the 77 CB550K engine.
You will not be able to use the choke knob and cable.
You will need intake manifolds, rubber carb couplers (Fore and Aft), and possibly the plenum that the rear coupler fit into) from any CB500 or Cb550 that is NOT a 77 or 78 model with PD carbs.
You will also need at least one throttle cable (and maybe both) for the non-PD carbs.
I suspect the jetting and internal adjustments of the 069A carbs will also need tweaking for proper operation, but a lot depends on the exhaust system you have selected.
That's all I can remember off the top of head. I'll post again if something else comes to mind.
Cheers,