A very rough estimate is 50-60 minutes, and of course, it depends on the bitrate. You can choose CBR, and then you know exactly how much time you will have, or you can choose VBR, and then you can estimate. I use a program called FitCD to calculate the bitrate. It's free.
DV converted to MPg is a difficult job for an encoder due to the colorspace used. You may want to use CBR at 2584 for the video and reduce audio to 160. That would produce the best quality, IMO. VBR should be used when you can not allocate the maximum bitrate to the encode. Others may disagree. Lots of opinions available here in this forum :) This is a roundabout way of answering your question as it should be easy for you to figure the time if you use that cbr bitrate.