As per past conversations, this length is still not necessarily going to be CBR (constant bit rate). I would still be using two-pass VBR (variable bit rate) for a 75- to 90-minute piece, that's going to be put to a single-layer DVD-R/DVD+R/DVD-ROM.
Again, I would refer you to use calculators.
For 75 minutes, look at 7500kbps (7.5Mbps), max 9000k, 384k audio stereo AC3 or MP2. I'd say you could use CBR if your content quality is really godo, and lacks lots of detail and/or fast movements. But for the best quality, VBR is suggested for anything over 1 hour.
ONE HOUR, not two hours.
This assume you're restoring or doing something else to the video, that necessitates re-encoding it. If there is nothing to be repaired or edited (not including removing segments, like commercials), then there is no benefit to re-encode. Just leave it alone, use it as-is.
Re-encoding to higher bitrate will not increase quality, and it might even reduce the quality some more, depending on content.