i am confused, are you working on a 550 or a 750?
74 550
The valve covers just unscrew to access the tappets. 8 of them. Can be replaced when on the bike.
Th cam cover can also be replaced with the engine in frame. But, if you don't put it back on right, you bend all the valves, and the engine won't run right anymore.
\Best look into getting a manual for the engine if you want to fix the it without creating a much bigger headache.