I'd be inclined to modify the frame (and bonnet if necessary) to accommodate the brake master cylinder and resovoir in their standard positions. The frame only supports the bodywork and provides brackets to hang things from, it isn't part of the chassis structure so it won't cause any safety issues with the handling etc, even if your welds fail. But if your brake pedal shears off...
I cut and re-welded my frame
just to allow my instruments to go where I wanted them -
Good luck finding a solution that works for your set-up.
