I got it! In an article at
http://www.columbia.edu/~em36/wpdos/wptoword.html#macroword, I followed the
instructions for putting the five new (well, old) fonts into my font folder
and taa daaa...no more @ signs in place of my quotation mark.
WP files with empty boxes or the wrong symbol characters when opened in Word
If your WordPerfect files display empty boxes instead of symbols when opened
in Word, or if you see typographic "dingbats" instead of multinational or
other symbol characters, then Word's import filters probably expected to find
some special fonts on your system, but those fonts were not installed.
To solve this problem, download this self-extracting archive of five
Microsoft fonts that shipped with older versions of Microsoft Office but is
no longer widely available. Download the archive program to a convenient
folder (such as your Desktop), run the program, and extract the five font
files to a convenient temporary directory. Then install them into your
Windows fonts folder by using the Fonts applet in the Windows Control Panel.
If Word is running, close it and restart it.
The names of the five fonts are: Multinational Ext, Typographic Ext, Iconic
Symbols Ext, Greek Symbols, and Math Ext.