hello!  i have a bunch of old school music videos ripped from ntsc dvd in their original vob format that i would like to convert to mp4.  these videos are interlaced @ 29.970, 480p.  now, when i import a video into the vegas timeline, the program asks if i would like to match my project settings according to the source file, and i select yes.  when i go to project settings, vegas tells me that the video's pixel ratio is .9091 and the res is 720*480.i

this is where i get confused about what settings to use in the mainconcept mp4/avc render box.  mpeg2 ntsc is 720*480, but the resolution that actually gets displayed during playback is 640*480, correct?  that tells me that i should use a res of 640*480 for the mp4 render, but what should the pixel ratio be to maintain the correct aspect ratio?  i've tried both 1.000 and .9091, but neither are correct.  the former gets close to being correct, but the video is squished vertically just slightly.  the latter completely zooms the entire picture out.  what am i doing wrong?

also, is keeping the video interlaced okay for converting to mp4 as long as i set the correct field order?  it will carry over from mpeg2 to mp4 format properly, right?

the reason i'm reencoding in the first place is to correct the black levels - they're washed out in the source files.  i would output to mpeg2, but the render settings are so overwhelming i have no idea what i'm doing.  everything from i and b frames to color spaces.  avc/mp4 just looks simpler, but i'd like to do it right.