From a purely mechanical standpoint, I can't imagine the Custom to be significantly different from the K model. The F (SuperSport) has a few different bits, and the performance is a bit quicker.
You should be able to upload it in the manuals section. Alternatively, you could send it to my email, and I'll figure out how to upload it to here. I'll send you a PM.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.