[HELP] Old AVI seems to have an unworkable frame rate, don't know what to do

[Selur]

The last two steps result in an incredibly long and slowed down file. The former three lead to a desynced file.

enable "Filtering->(De-)Interlace/Telecine->QTGMC Vapoursynth->Bob" if you want to keep all motion information.

is optional, 'if you want ....', without it the frame count will not change, with it the frame count and thus the filtering&encoding time will increase.
Without:

enable "Filtering->(De-)Interlace/Telecine->Deinterlace/Telecine Settings->Overwrite input scan type" and set it to "top field first"

no deinterlacing will take place, since the source is detected as progressive.

Using the steps I mentioned, I got a sync output.

Cu Selur