+1 pic of canvas. In all seriousness the shape will dictate layout. If they’re far apart you can bring it down deeper between them. If they’re really high up without laying down then the change in curve from the chest to top of breast could look funky if not drawn for your shape. Just a few things to think about. In an area like that I would recommend a freehand layout. You always get the best flow that way. But not all artists are capable of this method.
Women’s chests are incredibly hard to tattoo. One of my least favorite places to tattoo. Right up there with the spot just under the rib cage and the stomach. It takes a lot of effort getting lines in. Chest pieces look amazing though.