The part I will produce is essentially a box that will fit into the rear quarter window of a Jeep after the glass is removed. The bottom surface in the photo (next to the square dowel) will serve as a shelf. The square dowel is laying on what will be a vertical surface. 

Currently, the shelf is at a perfect 90 degree angle to the bottom flat surface in the plug. The opposite surface (the top of the box ) is about 104 degrees from the bottom in the lower portion, and 100 degrees in the upper portion. The small features outlined in red are at 95 degrees. I've read in various places that there is ideally 2-5 degrees of angle in order to release the mold from the plug. But I'm wondering if having greater angles on the opposite face will allow me to get the mold to release, if I start lifting the mold off from that side. I see two possible answers:

A) It will probably work
B) It won't work, and you should add a couple degrees of angle to the bottom shelf.  

Thanks for your input.

Ross

It wont be a problem, you've got the angle on the opposite side. If you had 2 faces opposite each other that were both 90 then you would struggle, but as it is will be fine.