Matt - I used a paperclip on the secondary actuator when I rebuilt the carb on my '78, back in, um, 1991. I have a kit, and you may have given me the inspiration to rebuild the carb again - or at least do the paperclip test - and then do a rebuild. I wish there were a more robust way to test a 2F carb secondary, but I've never found one.
Thanks for posting your results!
Colo Springs, CO