Become a hoarder , buy everything and anything related to a cb750. I now have (with my partner) about 11 bikes and a 20x30 shop full of stuff and still it's not enough !!
Basic stuff, ignition parts , plugs ect... tires , tubes , cables , handle bars , fuses , bulbs, oil , filters , seals ,(the shifter,kicker,tach drive seals can be replaced very easily) gaskets , carb parts (kits) exhaust donuts , swing arm bushings , tapers for the triple tree , a shop manual ,paper or digital , you see the list can go on and on !!!
Welcome and above all enjoy your new bike !!