Hi louieatienza,
Those interface brackets are just some pieces of sheet metal, should be fine I think. What's the difference of moving rails instead of moving bearing blocks? To me that sounds like pushing on one side vs pulling on the other: the end result is the same. I did change the riser plates and spindle mounting somewhat to get the spindle closer to the mounting blocks. I think this is as good as it's going to get without major design changes. I still don't know what you mean with gussets. When I google it, angle plates seem to show up most, but those are already on the riser plates supporting the gantry. I could make them bigger, but otherwise I don't know what you mean.