720x480 x 24bits (3 bytes) x 29.97 frames/second = 31,072,896 bytes/sec. Add 192,000 bytes/sec for 48k 16bit stereo audio for a grand total of... 31,264,896 bytes/second.
One minute of uncompressed 720x480 29.97 video with 48k stereo audio would be 1,875,893,760 bytes or about 1.8 gig/minute.
NTSC DV is compressed DV (about 13Gb per hour) which is what is on your DV tape when you film.
For DVD it will be NTSC DVD template in MPEG-2 render, then adjust the bitrate so that you can maintain quality as best as possible while still fitting your project on disc. (In general terms higher bitrate means higher quality but fills up the disc quicker. You have to get as higher rate as you can, upto a maximum of 9.8Mbs for video & audio combined, but still leave enough room on disc to get it all on)
Use the following
600/(minutes of video) = average bitrate for video & audio combined.
i.e.
600/90mins = 6.66Mbs
If your authoring program doesn't allow compressed audio you would have to allow 1600Kbs for uncompressed audio laeving an average bitrate of 5.0Mbs for your video.
If your authoring program allowed conversion to Dolby compressed audio at say 192Kbs you could use 6.4Mbs for your average video rate to fill disc.