I like the way you step off the path and make your own trail at times on the build. Having said that I cringe when I see the reservoirs under the cowl, it's a clean look but comes with some potential problems as delivered.
There have been several threads where the cover panel couldn't be properly sealed because of the thin glass on the body and lack of space to make a strong thin cover that will properly crush a gasket and become watertight.
The carwash and rain that runs through there finds it's way under the dash and in a couple cases shorted out the fuse panel and soaked the carpet.
The simple answer that occurs to me is a small curb. It can be as simple as a door edge guard bonded to the body panel with the but end seam at the lowest point of the shape. You still need to stiffen the glass on the underside and make a cover panel in a thin, strong compound shape but a curb will do most of the work. Start thinking about that now while you still have good access to that area and post pictures of your solution along the way.
Cool set-up on the brake system, thanks for sharing the build.
Dale Berry 7L Hemi33