ffmpeg deinterlace yadif=1 with NTSC to PAL converted VOBs

I have some VOBs that were stream copied from PAL DVDs, although the original work was NTSC produced in N America.

When converting the aforementioned I use ffmpeg with yadif=1 the deinterlacing does not work correctly

I have used YADIF=1 with NTSC and PAL sources , some of which had been PAL to NTSC converted it all works fine, but a handfull of these have been converted the other way NTSC to PAL and the YADIF=1 seems to fail on all of them.

ffmpeg -i “in.vob” -vf yadif=1 -c:v libx264 -preset slow -crf 17 -vf yadif=1,scale=960:720 out.mp4 -c:a aac -strict -2 -b:a 256 out.mp4

Is there an alternative that may work aside from 1/2 the resolution which is unacceptable? I get great results with other sources.