Couple of points of suggestion for you to ponder.
In the attached sketch, you can see where your bracket not only covers the end of the dovetail on the right, but also comes above the top of the slide area. As shown, this will cause you to loose valuable Y axis travel.
In the second sketch, you do not show any "thrust" bearings for the lead screw. The usual method is to use back to back AC (Angular contact) bearings at this point and also let the back end of the Y axis screw float (no bearing). It is short enough that this will not be a problem.
Good luck with your project and keep us informed on how your doing:})