Things to keep in mind when installing a longer arm:
if over 6" you will need a rear shock upgrade...new spring, re-valve, stopper This will keep you from bottoming out, especially if you ride 2-up You can get this done at Trac Dynamics or NLR
You will need to add a longer brake line...goodridge makes a modular kit...basically the line screws into the banjo fittings no need to cut and crimp
the other stuff you are aware of..longer chain, fender clearance, etc.