With the interlace filter, make sure you get the field order right. I used not to be so familiar with ffmpeg and I ended up using some GUI program I can't remember back in the day. See if the driver has an option for no deinterlacing because that happens at driver level.

There is no difference between 1⅓:1 and 4:3, they're just different representations of the same thing. Rounding the ratio to 1.33 produces a negligible difference but I would stick with 4:3 for a simpler pixel aspect ratio of 9:8 (1.125} as opposed to 150:133 (1.12782), assuming the capture is 720x480i60.

As for the zoom, TVs will have some overscan because different equipment caused various borders but the capture card should capture all 480 lines. You can check that the output is not vertically scaled by taking a snapshot in a high-movement scene (beware that most image formats are limited to square pixels so better force a PAR of 1:1 for this purpose) and observing if the interlacing indeed causes 1:1 combing as expected. Checking for horizontal crop can be done with another video source (camera, DVD player, STB, game console) generating a test pattern or at least a known image. However, if the vertical scale is correct and the content aspect ratio looks subjectively fine at 4:3 SAR, the crop is most likely OK.