I got the parts from a guy here in ATL. These are the same forks on 1977, just mine have that giant chrome fender.
These forks bolted right up by reusing the qt bearing cups. But as noobster pointed out there are some issues with running these forks and won't get their full potential unless you plan to do some other modifications, such as larger wheels and raise the rear to correct the telemetry. Or you could just keep them how they are and not care about the travel and build a YamaChoppa.