MissedAgain, good for you for helping-out a friend like that. I'd just like to say that I agree with Pompey on brevity. I would even go further to state that I believe a paragraph is probably all they expect and/or would want to read. From the way you made the form sound, it sounds like the comments section is not the central element on the form so it might not justify an entire extra page. Also, if you make it sound like you need to do "a lot of explaining," then that's bad. They're not simply going to believe you because you use a lot of words.
I guess you have to ask yourself, what are they looking for? A few suggested things, if applicable (some of these are repeats of what was suggested above): how long have you known him, how often do you see him, does he have a "good" family, ever seen him break the law, ever seen how he treats authority, does he regularly go to church, has he had the same job for a while, does he do any volunteer work, does he have "loving" children, mention he doesn't do drugs, doesn't get drunk, never seen him lose his temper, why he wants his rights restored (example, so he can inherit his grandfathers prized shotgun or hunt), keeps-up with current events so he has a strong desire to vote, participates in his children's activities (e.g. helps coach a soccer team).
If you're at a complete loss, you can contact the ACLU in your state. Don't laugh, they recently helped a friend of mine and his references with the restoration of his rights. You don't have to tell them it's so that he can own firearms.z