Congrats on grabbing hold of a Rocket. It's gonna be hard to stop grinning for the next few months.
Since you can communicate with the previous owner and this happens to be an early model, find out what Triumph recommended updates were done to this bike. A lot of early models had problems with the torsional damper bearing failing because the bearing was installed backwards, premature 2nd gear dog failures, necessitating a Triumph redesign and warranted replacement, overheated ignition switches forcing a redesign of the headlight wiring, bypassing the ignition switch. There were many other updates done. Also ask him if he has ever lubed the driveshaft to final drive splines. Should be done every tire change. If he has done this, the splines should be fine. If not.... A lot of these early issues were addressed on the 2010 models when the Roadster model came out with twin pipes instead of the threesome.