In your photo, on the top Nyloc nut there doesn't seem to be any threads showing. Those type of nuts don't lock unless there is at least one complete thread protruding through the nylon ring, so although it may seem tight it could work loose. Probably not an issue with the cover touching it as that will prevent it from loosening completely but it could throw the timing off (advance/retard) if the plate moves. Just something to be aware of or consider using different/smaller nuts with lock-washer/threadlock applied.
That is what puts me off the Boyers, it does seem to be a bit "Heath Robinson" from all of the stories on the forum LOL. I'm thinking of getting a Pipes and Stuff TCI in the hope that its a little better quality. I do like keeping Bitsy (I know, I've named my bike!) original but its getting to be a pain finding quality (ie; not chinesium) parts. Also the the aftermarket Advance Unit has a horrible advance curve, (its either fully retarded or fully advanced with no in-between) seems to me that the makers just don't understand how it is mean't to operate in conjunction with the engine revs.
Sorry for sidetracking the thread, maybe if I go ahead with fitting a TCI I'll start a new thread - with photo's! I know we all love photo's