The problem is that aftermarket indicators have a 10mm (I think) male connectors and lack the CB750's clamp that works with the chrome stems.
Note that I am fitting the turn signals to the headlight bucket on a '78, meaning I don't have stems to look at and hence may be proposing ideas that aren't possible.
As far as I can tell, these are the best solutions:
1. Weld a chrome universal clamp to a nut that can be snugged against the turn signal's male end.
2. Drill and tap the headlight stems to accept the turn signal's threads. I like this plan the best, but am concerned the stem may not be too small to house the turn signal's male end.
3. Find 2" long chrome spacers, then weld a nut to one end, and a hollow bolt to the other.
What have others done?