K, trying to figure this out. There are two planes that you may be referring to.

Checking the vertical plane, the top and bottom pieces aren't perfectly in the same plane how ever the delta is negligible. Maybe less than 1/8" of daylight at the arrow which trims out to nil at the bottom.

I doubt if you were referring to the face of the bezel but I checked it for giggles. Bottom s 20-degrees.

Top isn't quite that. More like 16-degrees. The measurement could be slightly off for the top because of the fancy woodland camo sticker that's on it.

Either way, I doubt if I'd have a problem if I machine the parts in the same plane. It's unlikely that the plastic bezel is perfect anyway. The way it mounts would hide any inconsistency. Think I good there. Is there another one I'm missing?