Why? is a good question I like to start out with.
There's nothing in the switched to switchless doc for this exact thing that I can find.
So you have e4e and e8e free on each controller? Both are supported cluster connections.
I would think that you'd eventually want to end up with just two cluster ports and 2 lifs per controller.
I would do something like this;
Cable the new 40GB ports to each other.
Introduce them to the Cluster broadcast domain and IP space.
I would think you could move cluster lifs 1 and 2 on each controller to the new ports. and remove the old lifs and ports from the Cluster broadcast domain and ipspace.
However... This is where I would check with support as the removing cluster lif KB is no longer available.