It is not very clear what you want to achieve with 24-70/2.8. My radical suggestion is use the 50/1.8, which you already have. The FL of 50 is in the middle of 24-70, and the aparture is faster. You just have to move forward or backward.
If you're interested, I'm selling the predecessor of the 24-70L, the 28-80/2.8-4L, which also produces image output of superb quality. IMO, the colour rendition looks better than modern Ls. You can PM me regarding the lens if you're interested.