"it seems as though when they mastered the LDs they removed every other line to shrink the image down to letterbox meaning any sharp edge nearly horizontal is broken severly, as can be seen in these 2 unaltered captures:"
This is the curse of NTSC - interlacing. You are only seeing half the lines of resolution in any given frame, which is why a lot of people like to try deinterlace (which is a bad idea.) PAL does not suffer from this, because it is progressive (all scan lines shown in each frame.)
As to IVTCing, VirtualDub will help you find the right cadence, which should carry through to the end of most of the discs. I don't recall if any of the discs have a cadence break prior to the end, but it's been a long time since I captured and processed the Def. Col. set.
"Each one has the deathstar THX intro"
Which intro is this???