I was flipping through the manual a noticed that the motor mount is off-center on the firewall, is that because of the sideways mounting?
No. It is because of the right thrust angle built into the firewall. The engine is moved to the left on the firewall so that the spinner will wind up in the center of the cowl. I doesn't matter whether the engine is mounted upright, inverted or sideways, it still has to be moved to the left by 3/16" or so.
Jim