If I had to do mine over again that is how I would do it. Steff's car was done this way and I really like it, ties in the upper shock mounts to the cage. You could also mount the motor plate to "struts" coming from the front bars to the frame rail, kind-of hard to explain what I mean. It's like the way that my motor plate mounts are done just with the front bars of the cage on the other side of the inner fenders. Call me if you want a better explination Rob.
Steve