Having gone through this process with my 82, I have a few tips for you...
If you want a headlight that matches the stock 83 GL1100 Standard, I believe you will find that the CB900, CB1000, CB1100 one is the same.
However, lots of Honda and non-Honda headlight buckets can work...the GL and big CB specific headlight bucket just have lots of room in the shell for stuffing electrical wires, so a smaller bucket will leave you looking for a new place to hide some of your wiring.
Slightly more difficult to find are the stock fork ears. Again, there are other Hondas of that vintage with the same diameter forks (GL1000 ears don't work), but getting a good pair can be tough, especially of you're looking for 100% correct stock appearance, which will require the flat "blade" style stems for the turn signals on the outside of those particular fork ears.
If you plan on adding a "police style" windshield and/or light bar, you may want to look at other ways of mounting the headlight...fork ears (along with the gage pod) inhibit easy installation of the mounting system used by most windshields and pretty much limit you to the ones that mount to your handlebars with struts.
If anyone has a clean stock GL1100 front fender (any color) I'm looking for one.