Bob,
I think you nailed it. Just make sure that the ballast is really good and  
dry. If moisture should get trapped in there, freeze thaw cycles could damage  
the trunk and require extensive repairs beyond what you have done.
As long as the cap is off, check the slot that the centerboard pin fits  
into. On Captain Bob's boat the slot was severely damaged (suggesting grounding  
or leaving centerboard down when launching)) and had to be built up with epoxy  
in a almost clay like form and then sanded smooth.
 
Rummy