Which field order should I specify for reinterlacing?

I have a HuffYuv file that's a VHS capture and deinterlaced with QTGMC via Avisynth originally to create a 59.94 720p Blu-Ray disk. I need to reinterlace to render the file for a DVD version and don't want to throw away half the video.

When using this script for reinterlacing should I specify TFF or BFF? I'm under the impression that BFF is "standard" but how do I verify it's correct for this file?

SetMemoryMax(768)
SetMTMode(3, 4)
FFMpegSource2("sourcefile.avi", atrack=-1)
AssumeTFF() or AssumeBFF()?
separatefields()
selectevery(4,1,2)
weave()

Thanks for all input