If you play it more vertical, it won't dive near as much. You need to move the strap button to the heel of the neck, but that's only going to get you so far. My experience with Gibson basses is that they like being near vertical, unlike Fenders that will poke you in the stomach if you try it. I play the 'Bird and EB-2 I have in an upright position and the Fender in a more horizontal position. My take on this is that Gibson neck dive issues and the bad rap come from people trying to treat them like they are Fender instruments. They aren't and have their own thing going.
Cranky old man. Cranky old bass. Cranky old amp.