I bought a 17" goldwing rim on a 4 hole cb750 hub on Ebay. Anyway, the spoke nipples are yellow colored and have the round end just like the sandcast spoke nipples. I can't say for sure if the spokes are GL1000 or late cb750 but they are a close match to sandcast nipples.
Might help someone. I did see sandcast style spoke kits somewhere so it might be just that easy to get them correct looking. CB750.com or Z1 I'm not sure.