I have found a company in JAPAN that has many things to make your CB750 like new.
It is a company called YAMIYA.
I was able to get the wiring harness extension for the alternator. New.
The one I had was greasy, hard insulation ,cracked insulation,etc.,.
After 33 years it really needed replacement. Not just repair.
Go to:
http://www.yamiya750.com/
On a Roadstar Adventure.