Nice looking machine!
I am just about ready to start building my first machine based on your great plans for your first machine (still acquiring parts). I have made some adaptations though (hope you don't mind..lol).
I shortened the base as I really didn't need that much travel plus I am really restricted for space here and the machine will have to be stored when not in use. I also noticed in one of your posts a comment about the anti-backlash nuts so I designed a set of spring loaded ones which should be easy to make on my 70's vintage Unimat lathe/mill/drill machine. I also noted your comment on gantry rigidity and will look into this once I get to that stage. I have considered an extra 'spreader' on the back of the gantry and also brackets/support blocks in the corners.
The only other change I am considering is fitting flange bearings on both ends of all the leadscrews so that the LSs are fully supported. This will require the motors to be mounted on brackets but I do not see this as a major problem.
Congratulations on the new machine and I hope you get to make chips/dust soon!