'78 KZ400 timing issue

So I'm a complete newb to all of this including engines of any kind so forgive my ignorance. I recently replaced my shift lever spring and didn't know to mark the timing on the gear on the crankshaft. How screwed am I? If I follow the timing instructions in the manual will I be ok or should I just take it into the shop to have them redo it? I talked to a guy that says I'll probably have to take the head cover off to get the valves dead center before I can adjust the timing but he wasn't sure and that sounds way over my head. I know for a fact that when I removed the crankshaft bolt it rotated slightly so I'm not sure if that makes things worse or not. Thanks for the help.

If you didnt mess with the cams or timing chain, then you should have no problem. The timing advance unit is keyed to the crank so it can only go on one way.

If you took the advancer itself apart, then it can be reassembled two ways. There you have a 50/50 shot. But there are photos here somewhere that show how the rotor should be facing on the advancer.

I'm assuming you only took off the right did cover exposing the clutch and shifter hardware. You did not split the motor open correct? Inside there are balance shafts that need to be timed and the timing chain for the valves/cams, but I don't think you could have gotten to that stuff geo just removing the right side cover.

I did not mess with the timing chain at all just the primary chain. I did take the advancer off but I took pictures before I did so hopefully that will help. Thanks for your help.