Hi, if anyone is interested, I have a CB750 chrome luggage rack on ebay. It is in brilliant condition. I bought it to see if I could fit it to my 1977 CB550 but its way too big and the hole spacings are not right. I have added hole spacing sizes etc to the pics. I have no idea which model 750 its from but the sizes might give someone a clue as to whether it will fit their bike
Cheers everyone