Brackets for holding carpenter's level

My basement floor isn't even. I wanted to make sure I had a level surface, even if I had to move the layout around, because it is a switching layout and a piece of rolling stock shouldn't move once it is spotted. Since there's foam for the scenery, I no longer have a flat surface. I found some straight brackets and screwed them to the underside of the layout benchwork. By rotating them out, I have a place to set my large carpenter's level. I can then use the leveling blocks on the legs to make sure the benchwork is level.