This site has the Factory Service manuals in PDF format available free of charge. Go to the "front door" of this site, and look for a posting near the top that says Manuals.
There isn't much you can do to set the timing on the DOHC models. Timing chain is easily done, and explained well in the FSM.
Welcome to the forum. That bike looks like fun.
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.