1. Dr. Gonzo is from NTSC, which is maybe a dozen or so frames longer than the video you've got, so you may have audio sync problems.
2. Instead of 34 hours, why not give DVDShrink a shot at it? It'd be quite a bit faster. As for quality? Since you'd only be dropping from 4.5GB to maybe 4.2, I'm guessing it'd be pretty good. Of course, when you reply and say it's better to re-render from the source, you're right. And it's your project. I'd do the same, actually.