I would replace the down tube if it were my car. Safety is not an area to skimp on, it's not worth your life. A crimp in a tube becomes the weak point, and the point of failure in an accident. It looks to me like the builder either didn't have the correct die to make that sharp of bend or they tried to use a pipe bender instead of a tubing bender. If you paid someone to build the cage I would take it back and have a heart to heart talk with the builder. And as others have stated the cage can't be welded to the A-pillar. Good Luck!