As for someone I think would make a good voice actor but hasn't yet... Gee, that's tough, seeing as I don't think there are a whole lot of movies I've seen with actors that I really liked who haven't turned out to do have done some voice-acting at some point or another.
That and the fact that I can't think of any people who have "good" or "bad" voices, since they'd be fine as long as it was the right character. Mmm... I liked Kurt Russell in Miracle, it'd be interesting to see him do a voice-acting job (if he hasn't already). Can't think of anything else, really.
I'd been browsing the forums for a couple hours before joining. Thanks for the compliment on my sig; I quite like your avatar. I can't draw, so I had to settle for the one Guido picture that I could find on Google. 
I knew I should've paid more attention during the credits. From what I can remember, now that you mention it the principal did sound like him. Even though he had such a small part, I always remember the principal because the line about Chicken's dad being the former baseball star seemed so forced. 
And if so, was it by any chance super-villain-in-disguise Bernie Kropp, out of dislike for his employer because of always siding with Dash, who broke into his house?
....anyways, it's from The Fly (1986).