That will be tough. The mounts for the Norge and Breva side cases (panniers go on the front wheel) are different. Give me a few minutes, I'll go out and take pictures of the two of them.
EDIT ----
OK, while I was out taking pictures I realized you are probably talking about a big Breva and ours is the baby Breva (750) so none of this may apply. I'll put up the pictures anyway so you can see what the Norge sidecase mounts look like on the bike.
You will also need the exhaust lowering kit when fitting the sidecases. This is just a strip of metal with a hole on each end to let you hang the muffler so it doesn't touch the bag. I am not familiar with the Big Breva so I don't know how your muffler will interfere.
Please pardon the states of disassembly. Much motorcycle maintenance going on.