That isn't going to work.
You aren't going to be able to mount the pub.edb on another server. If you
want the information, you'll have to set up a recovery server that has the
same Exchange org, same server name, same Admin Group name, etc. only then
will you be able to mount the pub.edb
That, or you might look at some 3rd party tools. Quest has a GREAT tool
called Recovery Manager for Exchange, but I don't know offhand if it works
with Public databases. I do know it works with Mailbox databases, and it
has the ability to read directly from tape, or offline edb files. Pricing
is very reasonable, too.
Read my blog!