You can’t IVTC it successfully, because it’s field blended. You need to use something such as SRestore(). There are alternatives, but they are all much of a muchness.

LoadCplugin("C:\Program Files (x86)\AviSynth\plugins\yadif.dll")
Mpeg2Source()
AssumeTFF()
Yadif(mode=1)#or QTGMC or whatever
SRestore()

I get confused about the history of the different TV versions. Was this the version that was edited/reconstructed in PAL and then converted to NTSC or was that the RIC? You might have to adjust the script to specify a frame-rate. At present, it’s returning 25fps.