Welcome to the fun!
The stock rear CB750F0 swingarm is rigid as a bridge. Other than installing proper bronze bushings in the pivot, it is among the strongest swingarms ever built. The OEM bushings, however, are not in that category, so many "urban legends" proclaim the swingarm is "weak" when nothing could be further from the truth. The OEM greasing system had to be used on schedule from Day One of the bike's life, and almost 0% were actually so used. That's where the "weak swingarm" lie comes from: lack of maintenance.