That tank style was common for both 550 F models and the 77-78 K models. I expect most of what you have originated as a K model. That's a K side cover in the last picture. But, the 77 model K3 came with PD style carbs quite different from yours, for sure.
087A carbs are from a 76 model Cb550K. #100 mains and #38 slows, with air bleed adjust pilot screws, hollow tipped and cross drillled. These should work better with your pods and exhaust than the 069A F model carbs. The carb separation spacing is different between the style carbs you have and the PD carbs that came with it stock. Have you tried mating them to the carbs yet? If not, you either have to get manifolds and rubbers from an earlier machine, or find PD carbs to put on it.
Cheers,