If you buy used parts, make sure that you get everything listed in the instructions linked above, including the wiring harness and the odometer knob. You proably won't need the wire to the igniter, but you do need everything else in the kit.
Wow, that's one hell of a job you did/had done on that bike. Good for you for seeing it through. You probably fixed something that was defective from the day it rolled off the assembly line.
Whoever buys it will probably not appreciate in what good shape that motor now is.
The seal is a simple one-minute replacement.
Removing the clutch cover is more of a job. The oil has to be drained, you have to remove the breather hose on top, then break free the cover (if it's never been removed), then plan to spend several hours carefully scraping off the gasket bits...