Ok, so I did some digging. Went through all the part fiches I could find and notated the part number for the 500's, 550K's, and the 550F's. Hopefully someone will find this useful (or at least interesting).
The 500K0-K2 had part number 22100-323-000. The CB550K0-K1 had part number 22100-374-000. From some searching online these look to be the same exact part. I know Honda pulled parts from other bikes and renumbered them. My assumption here is they used the 500 clutch basket designs on the early 550's.
The 500K3, 550K2-K4, and 550F-F2 all use 22100-390-000. This is the basket with the wider notch at the top of the basket. So, it looks like they made the switch in 76 to the new design. I looked where I could and it doesn't look like a superseded part.
Bike Basket Part#
CB500K0 22100-323-000
CB500K1 22100-323-000
CB500K2 22100-323-000
CB500K3 22100-390-000
CB550K0 22100-374-000
CB550K1 22100-374-000
CB550K2 22100-390-000
CB550K3 22100-390-000
CB550K4 22100-390-000
CB550F 22100-390-000
CB550F1 22100-390-000
CB550F2 22100-390-000