Any CB500 71-73 Cb550 K0 74. But, the petcock is a different style. Works fine, though.
Direct swap would be a 75 or 76 CB550 petcock and all.
All the F model (door) tanks 75-77, will fit onto the frame, as will the 77-78 (door) tanks. However, they are longer and require a seat length change. The last two years of CB550 (77-78) production used a single outlet petcock with a T fitting to feed the carbs of the 77 F model (the K model carb only had on feed nipple.)
Cheers,