There is one flaw with the Volks body which is that since they were not designed to support heavy pullip heads, the torso joint tends to start flopping after a bit, just like old type 1s. (By the way, you can easily fix type 1s by screwing the lower half of the body up into the torso). This should take care of that without losing any poseability.
1. Take off the chest plate. You won't even need to remove the head, it'll pop right off. While we're at it, isn't that a wonderful skintone match? Better than the stock body she came with.
2. See the skinny single shaft? No wonder it flops! You're going to alleviate the stress on the shaft by cutting little strips of foam approximately 3/4" long and 1/3" wide.
3. Fold two pieces over, and stick them in the sides so that the folded part is on the inside. The foam wants to be straight, so it will push up subtly on the sides, balancing out the torso from within.
4. Fold 2 more pieces over in the front. The top one isn't really there for any reason other than to keep the one below it from vanishing up into the boob cavity.
5. Replace the chest plate.
Ooh, look at her standing up straight without any support!
. And you can even tilt her slightly without her flopping all the way over!