What I did was just followed the above method to see what fonts for the blog text are available for 2 blogs with 2 different templates, one using New Blogger Minima template modified to 3 column and another using Rounders 4 template modified to 3 column.
Result: In both cases, I found the choices of fonts available was just 6, and were the same for both templates. The fonts available are:
The next question would be if it is possible to add more choices by editing the CSS (Cascading Style Sheet) of the template, but this will take longer time and success is doubtful. That would have to be put off to the future, if I ever remember.
Update: I had a quick look at a template of one of my blogs, and perhaps it is not too difficult to test. I may have to edit lines like
<Variable name="descriptionfont" description="Blog Description Font"
default="normal normal 78% 'Trebuchet MS', Trebuchet, Arial, Verdana, Sans-serif" value="normal normal 78% 'Trebuchet MS', Trebuchet, Arial, Verdana, Sans-serif">
If the above is sufficient to give you an idea as to how to go about trying, hope you share your experience with us by leaving a comment.