Just picked up the '78 CB550 today. The Iowa title is messed up (a previous buyer signed the wrong line and used white out trying to make it right), but there are plenty of useable parts and it does run (rough). Compression seems to be good. I think it just needs a good tune up and clean carbs. The windscreen is missing on the fairing.
Although it isn't shown in these pics, both side covers come with the bike as does the primary chain cover.
The chrome 4-1 exhaust is really pretty clean. No corrosion has eaten through.
I am looking to take this engine and use it in my CB500K frame.
Paid $200, and I think I'll get my money's worth out of it.