Ok, so update... I know... I've been so busy trying to get the SV running again, I neglected the poor CB.
Anyhoo, started tearing stuff apart today, to transfer the bike inside.

Anyway, I took off the top triple, and found this number:


It's on the locking mechanism. Problem is, it doesn't look like any of the examples on the hondakeys.com site, and doesn't appear to match any sequence. I'm stumped. Is this the wrong number? Do I need to tear something else apart?
Also, how hard is drilling out the lock for the seat? Pretty easy?