Let’s not put the cart before the horse! Before we talk about chopping, you need to decide how tall you want this tree to be. And, how thick of a trunk do you want.
Then, we can take a look at what branches you have, and determine which are keepers, and which can be used as sacrifice branches.
What style do you want? Do you want taper?
They don’t back bud on old wood.
All these things go into the plan, and THEN you can think about pruning.
Something to bear in mind: When you are building a trunk and primary branches, maybe the heaviest branches should be sacrifice branches rather than primary (keeper) branches! The reason is if you have heavy branches that are, for example, half the thickness of the trunk, they look out of proportion. They make the trunk look thin. The best way to make the trunk look heavy is to have thin branches! That’s very important when designing conifers.
Another thing to keep in mind when picking primary branches is the angle they have coming off the trunk. Atlas Cedars look best when the branch come straight off the trunk, rather than grow up, and then bend down. The earlier the branches can be trained into position, the better. So, on that picture that Sorce posted with his suggested pruning, he suggested to prune the small branch, and keep the larger one on the right. Well, I might disagree. It’s hard to say without having the tree in front of me, but the keeper branch has two faults: 1) it’s very thick relative to the trunk; 2) it’s growing up at steep angle, and you’re not going to be able to bend it down to horizontal. I would agree that it’s on the outside of the curve, whereas the thinner one on the left is on the inside of the curve, and from that aspect, it’s in a better position. So, perhaps another side might be a better front?
And the lower trunk is awkward from this view. I think there’s a better front than what we have been shown.
Good luck with it!