I can't tell from your photo, but it appears that your mocked-up rear axle has a pretty severe upward pinion angle. At ride height, the trans should be 3*down, and the pinion 3* up.

I also noticed that most of their applications placed the 4-bars inside the frame rail instead of outside. Are you OK with tire clearance, wheel backspace, etc? Was there a particular reason you set it up on the outside of the frame?

By the way, the reason that 4-bars are usually equal length an parallel is so that the axle moves up and down in a straight line. If they're not parallel, the rear axle tends to rotate about a point where a line drawn through the two bars meets in space. Of course, ladder bars work the same way, so it's probably not significant in this case.

I have NEVER seen a shock tilted backwards. I don't think it will cause a problem, but it gives the suspension a very odd look.