Uneven walls in kitchen?

I'm about to install new cabinets in my kitchen and I've noticed that the walls are not parallel. There is a 1.25" difference from one side to the other and it is a "U" shaped kitchen. I'm wondering if I should keep the cabinets tight against the walls or shim them out to be parallel. The walls are drywall on 3/4" fairings attached to brick - so I'm also curious if there is a better way the attach the cabinets than tapcon screws. The old cabinets were mounted with plastic anchors but I was told tapcons would be better. Thanks