there isnt a lot of clerance above the 8mm smooth rod for the Y Carriage (unless your going to raise it up a little) here are some pics of the plastic parts you can see the smooth rod sticks out the top:



you can also see the spring configuration for leveling the bed I.m going to remove that completely on the new build and just use a fixed bed (still held in place with the 3mm screws it just wont be adjustable) and I will use a inductive proximity sensor to do the auto-leveling.