I can recommend the '74 swing arm in the '71-'73 frame. You can grab the early arm and literally twist the rear end. This causes the famed 'CZ hop'. In '74 they moved the steering head forward which puts less weight on the front wheel = poor turning.
As '74 swing arms are rarer than whatever, I use and recommend a GMC chrome moly arm. Expensive but they make a huge difference, you feel so safe.
Cheers,
D.