You do know you need a new shift drum, too. Very common back then.

Based upon lineaway's comment, I think I better understand the picture you posted previously; it sure looks like a chunk of your shift drum is missing! The channel for the pin of the shift fork needs to be complete and well defined. And without a shift fork pin - as you state - there's no mechanism by which the rotating shift drum can move the forks to select a gear. Sorry to say, but you transmission appears to be in need of some serious repair.. But a few parts should get you shifting right.  Good luck.