My '83 Nighthawk has the locks too.
No matter as you may BE RIGHT.
http://www.cb750c.com/publicdocs/CB...erviceManualChapter13FrontWheelSuspension.pdf
Look at the '79 K model there which does NOT have the pieces, the K fork is the same fork as F in that year other than paint and maybe caliper hole location, one is likely blank. There is no mention of the extra pieces in the assembly work.
They would have had to make a change there and how to tell?
You will have to assemble parts and look at how much room you have between the upper triple bridge and the top of the one lock nut you want to use. They should hit (so the triple locks the nut in place) when the back main stem nut is tightened up. If you use the upper lock pieces in question you need another 1/4"-3/8" or so for room to install them meaning the triple will not touch the lock nut at all and why I say tightening up on that will likely crack the bridge. If you have a lot of space there you need the parts. Look in that link, one pic shows the install from the side and it looks like the triple does hit the top of nut, it should be fairly easy to see. I also found a blowup of the triple area that did not show the pieces at all like they are not used.
Page 13-2 shows evidence of not using the parts, the part at top about hard steering being top nut too tight means they are relying on it to lock the lower locknet in place rather than the two missing pieces.
13-20 and 13-24 show the height the fork tubes clamp in the triple at, or dead flush to maybe 1/8" of fork tube sticking out of the triple. You need to know that in re-assembly to have the triple at correct angle for the extra space checking to determine if you need the extra parts or not.
13-25 to 13-28 detail the taking apart and putting back together and no mention of the extra parts at all. Your F uses virtually the same parts, I would not worry about the service manual being a K one.
I apologize for running you through the mill on this, it is apparent now they did it in two ways to me. A careful looksee at assembly should tell you whether you need the extra parts or not. If the triple hits top of locknut then you don't use them.
Sorry for all the fuss.