Clem: After some 40 years I put about 27000 Km on my SFO - So that might be your answer - However; I did hundreds of thousands miles on various motorcycles in my life and a survivor - That SFO was the one I kept and probably my favorite till I quit riding 3 years ago and then I sold her. No more motorcycles - Quit riding at 70 years old.
Tore her apart twice during them years. Rotten gaskets and rotten rubber seals where the main culprits for rebuild.
Had to wash the clutch pack with lacquer thinner and rough with 280 grit after I gummed it up with Teflon. Tack welded the starter clutch back plate - Wire the starter relay to ground through the transmission neutral switch and replaced the pistons, rings, touched up the valve seats, reground the valves, honed the cylinders only because the Head Gasket and main seals rotted out. Didn't have to replace the valve springs or change the rubber crush drive rubbers.
Other then I would highly recommend replacing the Valve Springs with every engine tare down or your NOT getting close to 8000 rpm.