Anamorphic stretch option for old .dv files?

I have a number of old .dv files exported from various source material into the old iMovie 6. All 16:9 clips are unstretched anamorphic. If I bring these into Final Cut Pro, I can unstretch them simply enough, but the quality is low, and running that through TVAI helps. BUT, I just realized that TVAI does a MAJORLY better job on the same clips if I import the original .dv file, and not an edited exported 264 file from FCP. (Maybe it’s a pixel shape thing? idk)
I’d love to get the far better upscaling from TVAI that it offers on these clips when importing the original .dv files, but I’d also like to be able to edit freely in FCP.
Is it possible for TVAI to offer stretching the anamorphic .dv files in its processing? Now the only options I see are crop or letterbox

You could run the file though something like MKVToolNix and add a 16:9 flag. This way there’s no quality loss and VAI will detect the flag and stretch appropriately.