Welcome to the forum. Very nice looking bike you've got there. And I'm not just saying that because I've got one too.
Hit some of the links in our
parts sources thread. The brushes should be pretty easy to find. 79 to 82 should all be the same. Watch out on the petcock though, they made changes to the thread size during the model run (79-82) so if you get one for another year it may not fit. Sorry, I don't know the size off the top of my head, I just remember some other member's getting used petcocks that didn't fit.
89 VN 750A - Given to son-in-law
79 CB 750K-sold 3 May 21
78 CB 750K
77 CB 750K
77 GL 1000 x 2
77 CB 550F
Holton, KS, US