Great job! Will try updated version soon and really wonder at new behaviour.

Just an idea: why not generating a metapackage too?
First of all: use correct version number for updated busybox. Then your mentioned metapackage will break, therefore you'll need another metapackage providing the needed version and itself depending on your version. That should do the trick imho. I don't think there will be issues having several versions of busybox installed. They shouldn't conflict, but your package should have a slightly different name of course. Maybe you can even provide a different version string within the same package but I'm not sure. Debian archives are so powerful, I sometimes could swear they even make coffee