Sounds like a big implemention with no short answer to it. But as a starting point, you can set characters max slope angle to 90 so he can walk any surface. Then you need to have your animation blueprint check the slope angle to change the animation to wall running animation, and have a transformation animation where your character rotates 90 degrees to walk against the wall. Otherwise the transformation between ground walk and wall walk will look just buggy, no matter how complex blueprints you have set up.