I think the biggest difference between your current bike look and the classics you posted are - wheels, fenders, and shiny black vs matte. Your fenders/wheels are black; on the classics they are chrome; all the black is shiny on the classics. But I am not suggesting chrome on yours. Maybe a chrome tail light, a chrome "tuning fork" emblem on the side covers, or silver/aluminum paint on the fenders might help add some visual interest (might make them look like alloy). I think I'd leave the wheels/forks/headlight mounts/handlebars as is. Maybe contemplate gloss black for the side panels/tank/headlight shell?