Hey Sandy,
In v8, check these settings:
Preferences>General and the second section is Name Inversion Options
Jr. should be the first one in the Suffixes list
I just tried inverting a name that has no period after the Jr -- and you're right, that doesn't work.
The Chicago convention has changed, but this hasn't.
Here's what I'd do:
Find (Ctrl+F), the suffix Jr with a space after it instead of the period.
Replace with Jr.
That should find and replace them all. Then -- once you have them in that group, they're likely all in the Main column.
Click on the word Main at the top of the column, do the inversion and they'll all do it at once.
Fun trick that!
Of course, you'll have to have all those names un-inverted to start with...
Deborah