I had one just like it a few years back, in just about the same condition. Congratulations, and welcome.
Take some time, and download the Factory Service Manual from the home page.
The search window is your friend when it comes to problems your bike may have. Here are the obvious answers:
Your carbs cannot be too clean, internally. Especially the jets.
The DOHC carbs run best with the factory air box. You can use pod filters, but be prepared for a LOT of work and struggle.
Vacuum problems around the carb boots can be fixed with good clamps, or a diluted wintergreen solution to soften up the rubber.
It's spelled cafe, but doesn't rhyme with chafe.
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.