Well, of course, if you never intended to watch it in colour your approach is perfectly valid, in fact, it is only because the colour standard is 'digital' in nature (i.e. the colour is encoded in the PCM values and need to be extracted digitally) that the sync is not used and an assumption is made that the data starts on a frame boundary.
In truth the standard allows for this and my software should in fact allow for this at least by providing a mechanism to adjust the sample position so that line and frame alignment can be achieved, but since it was written with the assumption that the source material would only becoming from my other application Video2NBTV, it didn't seem necessary at the time.
Yes the new start position should be immediately before or after the missing sync pulse (depending whether the sync is placed below or on top of the picture, in this case it doesn't matter).
Be aware though that in the first few frames of that clip there is black level immediately before and after the syncs for some reason, this makes editing the material by eye difficult and I had to do it by calculating the correct sample position based on the start of any arbitrary sync pulse.
Cheers from one duffer to another
(must work on that swing)