Coming together Mike got just a couple of suggestions.

#1 Build in more adjustment, for instance at the moment you have no way to adjust the alignment of the Y-axis (long axis) ball-screws up or down, in and out you can shim but because it looks like you plan to bolt directly into the steel tubes then you have no up/down adjustment. It would be better to make those spacer plates wider so you can machine slots into them on either side of the BK block and make the BK bearings bolt directly to these, then bolt the spacer plates into the main tubes.
Balls-screw misalignment is the #1 cause of missed steps and stalling motors at high feeds and if too badly aligned bent screws so having plenty of adjustment will pay back big time when setting up the machine.

I can't see the X-axis clear enough but I suspect you could have similar issues there as well, esp around the ball-nut mount area.?

#2 Similar and related to adjustment is the motor brackets would be better bolted to the frame rather than welding which is how it looks like you plan on doing it from the pics.
A bolted setup also gives you more choice on belt lengths and again alignment, plus if you ever want to fit larger motors ie: Nema 34 then it's easy to swap out the bracket.

Other than those couple of things it's looking good.