Mike- I wish I knew more about the bemans, but what I do know is that yes it is true that if your shaft is a little too short or too long, you can adjust point weight to accomodate, but if your shaft length is way too long or way too short, you will not be able to adjust enough within a reasonable shaft weight. And when I say "way too" this could mean only the difference of an inch or so. Again, i'm not familiar with the bemans, but if 400's are 400 spine, I would bet that they are too stiff and all the point weight in the world won't make them fly right.
good luck, BigJim