An X ring chain, like an oring chain, is too wide for the CB550 and will grind on the engine cases.
You would need an offset front sprocket to regain the needed clearance.
The 76 CB550F uses 100 links with the stock sprockets. A 530 chain off course.
If you insist on an o ring/xring chain, the you should convert to a 520 type. This will, of course, require new 520 sprockets, too.