Build volume is incorrect / Right extruder cannot reach X=0

[evilC]

Machine width is set to 324
The left extruder cannot reach X=324.
Furthermore, the right extruder cannot reach X=0

The advertised build volume width of 300mm is not possible for an IDEX print as it stands
The available range of the left extruder is 0 to 310 (With a gap of ~9mm between it and the parked right extruder)
The available range of the right extruder is 11 to 325 (With a gap of ~7mm between it and the parked left extruder)

So if you moved the printable area ~11mm to the right within the moveable area, full-range IDEX prints should be possible

This appears to be a mixture of a Cura plugin issue (Machine width should be 300, not 324) and a Marlin issue (print area is incorrectly positioned in moveable area)