Use the move copy body command. See tutorial below.
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Go to insert>features?Move/Copy Body, then click on rotate/translate and then from the rotate pulldown you can rotate the body. So for example if I rotate the part shown by the x-axis, by 90 degrees, it essentially moves the front plane to the top plane.
You may also need to do a second move copy body to translate the body into the right position, so that your shadows are correct.