When it comes to fabrication going overkill is NEVER a bad idea, it could save your or someones elses life. If that coilover bracket breaks especially at highway speeds you are going to lose complete control of your truck.
You need to redesign that mount, I would have welded your hoops to 1/4" plate and then welded that to the frame. This would give you much more surface area holding onto the frame. You can also think about tying both mounts together over the engine, this would dramatically increase the strength and stiffness of your suspension setup.

Hope this helps, Cage makes great products. Also are those the tires you will be running, if so you probably want to lower the truck down as your center of gravity is pretty high right now.