The only suggestions I can offer would be in regards to the gantry end plates. While it appears that you have cut them back (L shaped them) to get both ends out of a slightly larger piece of material I would recommend against doing so. Flexure can happen in many areas on a system and one of the more overlooked locations is the gantry end plates. Stiffness in the end plates is relevant to controlling lateral sway of the gantry and controlling lateral sway is relevant to keeping the side of the bit in contact with what it is cutting rather than skipping off the surface. Carrying them out full width will double the stiffness resulting in a stiffer machine which leads to a better cut.

The other item in regards to end plates is the height. While I understand the urge to make the gantry high enough to cover all the "what ifs" doing so only reduces the stiffness of the machine. And the loss of stiffness in this case is not a simple linear loss, the losses are exponential. Doubling the distance between the X and Y rails does not merely double the flexibility, it increases it 8-fold. This is why it is imperative for those seeking the greatest possible stiffness in a machine to reduce the vertical rise to the absolute minimum necessary to do the work the machine is designed for. If you are needing to do thicker materials on occasion, it is better to put a false bottom in on your spoil board and drop the bottom out to allow for thickness than it is to jack the gantry up.

 

Honestly ball screws are overkill with V-wheels and V-rail. I would use linear bearings like MGN9 or 12 size.
Can be found for not much more than the cost of a set of full price V-wheels these days.
aliexpress linear rail

OR just go V-wheels and dual-belt like a standard OX heavy duty (the HD uses 2080 or C-beam for all)
the dual-belt is not the limiting factor in the OX

Also you really won't need that much torque for steppers.. any crashes and you will bend and break stuff with the screws for sure.

 

Not worried about breaking the screws, but you are probably right, just have strong end stops! 397oz-in steppers at 48v (high speed)
I worry with mine that i will strip the belt when i hit an end stop, even with 269oz-in it's amazing how strong they are.. but with 1605 screws they make a whole lot of force.. It's easy to get carried away Jogging!