Nomath- It might do you some good to measure your GL front wheel and compare to your CB500s front. You may find that the GL wheel with rotors mounted is wider than the available space between the stock 500s forks. The GLs use a wider fork spacing and thicker diameter forks so you wouldn't be able to slide in a set of GLforks into your triple trees nor would you be able to put GL lowers on your 500 tubes. You probably could fit the entire GL front end including trees into the stock 500 head tube (The spoked GL1000 front end fits, but I am not certain about the later comstar GLS)The F2/F3 750s used comstars with dual discs up front and a single disc in the rear, so perhaps some parts from these bikes might help you with your swap. Overall, using the F2/f3 wheels, forks, calipers, rotors and swingarm would certainly be a much more straight forward option to putting comstars on your bike and upgrading the brakes. . . . . . . .