Which Zimbra version are you using?
I am using Zimbra 8.8.15, if you are using old zimbra version, please google for the exact path.
You should put all your customization config in sauser.cf as Zimbra's suggestion.
i'm using zimbra 8.8.15 same with u ,
by the way , i just run command :
chown zimbra.zimbra /opt/zimbra/data/spamassassin/localrules/sauser.cf
but i can't still test :
and restart my zimbra antispam
but, dunno if that scripst is running or not.