MVtools scene detection for a clean cut? (1080-50i to 720-30p)

[nhope]

I have a bunch of HDV 1080-50i clips on my Sony Vegas Pro timeline and I'm converting them to 720-30p UT video codec format to mix with footage originating from HDV 1080-60i by frameserving to the following script, then VirtualDub. It will later be rendered to H.264 for the web.

AviSource("d:\fs.avi")
AssumeTFF()
ConvertToYUY2(interlaced=true, matrix="Rec601")
QTGMC(SubPel=2, EdiThreads=2)
super = MSuper(levels=1, pel=2)
MFlowFps(super, QTGMC_bVec1, QTGMC_fVec1, num=30000, den=1001)
Spline36Resize(1280,720)
AssumeFPS(29.97)

The quality is great. However at some of the scene changes in the 30p output I get a clean cut, but at others I get a blended frame. This is not a big deal as the eye generally glosses over these rapid transitions between scenes, but I was wondering if there is a smarter way to do it whereby I always get a clean cut?

I guess one solution might be to duplicate a frame instead of blending at those transitions, but I fear that might look less smooth during playback.

I guess another solution might be to drop a frame, although that would make the video shorter and I would prefer to retain the overall length of the video so I can still sync 50i and 30p to audio on my timeline.

So it seems the ideal solution might be to somehow detect which transitions are going to render a blended frame, and then at those transitions to generate a new frame by either looking just backwards at the preceding clip, or just forwards at the following clip, depending which of those 2 clips' ends is closer to the cut. I hope that makes sense!

Possible? Or should I just live with the blended transitions?