Oh well, what's done is done and can't be undone.....
Thanks for the brilliant sharp pictures, 5 pictures, 5000 words, I will be brief...
As Mike says, SHORT OUT plug leads to kill a cylinder.
The ignition system should be considered to be FRAGILE, DO NOT disconnect a plug lead with the engine running !
Are your plug leads yellow and black ? Suggesting a non standard HT coil, no matter.....
DOT. More or less perfect position if already adjusted, auto adjusted by the spring loaded system. Good length of slot left as well.
Do not be tempted to help, over adjust that spring loaded auto adjust system. Over adjustment just wears stuff out quickly. The "slipper A" that sits between the balance chain is vertually unobtainable, it costs an organ. The "rubber" on it will be rock hard by now. Over tight engine chains make a sort of winning whizzing rustling noise, which I have heard in one of your videos when the throttle was blipped.
The dot is in a good position.
Make sure the oil pump chain does not touch that hexagonal tower, the oil pressure relief valve, that lives just under the oil pump sprocket. They very very very rarely stick open due to spring.
Right exhaust valve rocker arm looks a little "dry" and a bit discoloured at the cam end. The valve working clearance adjusting screw looks a bit deep in the valve end of the rocker arm. This suggests a possible lub problem, but that's for later. I suspect the rocker arm can contact pad may he quite worn. I will listen again to the knock.....after finishing this post but do not think this possible problem is your knock.
Check to make sure that the oil pipe is not contacting the camshaft, it looks as if it is quite close.
Pictures of valve springs and view from other side would be good. Do the valve springs have a yellow paint marking at the top, all of them ?
See my picture at bottom, these are "stakable nuts" from the car world. Does the slotted clutch nut look like them ?
CMSNL com. Cmx450c rebel 1986 (g) USA California, is this your exact bike ?
Slotted nut, is that a wire clip on that nut ?
No clip is shown on CMSNL exploded views....
The blueish washer under the slotted nut, can I see some writing on it, maybe "outside" it part of that word ??
To me the slotted nut looks as if it's on backwards.....
Cam chain adjuster.....is there a rachet system on the two parts, lines going across from side to side to "rachet" ?
Also, a bright area, maybe steel wire or foriegn object, close to the cam chain adjuster ?
Engine run with cam cover off ( but clutch cover etc. On, oil to level ) This is easily doable but messy. You will see oil flow to camshaft ends. Oil flow should be good and about the same side to side, oh hang on, yours had external oil pipe, will have to check as oil flow may be thru those pipes only, I will come back with oil flow diagram for you.......but engine run and oil flow check easily possible, but Messy !
As Mike says, with clutch all together, clutch cover on and oil to level, in gear with clutch pulled in ( disengaged ), and back brake on, all gearbox and clutch hub will stop turning, but, the clutch basket will still be turning cos the crank is cos the engine is running.
I will listen again to the knock vidio...