If the HDZ mount plate is wider than the stock mount, it would reduce your X travel a little bit.
Initialize your machine, then reset all offsets. Your display should be showing -5, -5, -5 (mm) or -0.196 (inch). Move the machine to the far front left with Z down as far as it will go. values will be negative, but that is your work envelope.
For a long time when a new version of CM would come out C3D would set the travel slightly smaller than maximum to compensate for the Suckit Dust Collection that had ears that stuck out wider then the Z carriage. The Suckit is no longer made for Shapeoko but there are still a lot of them out there.
As Tod suggested move your machine to the limits and see how far it is traveling. You can increase your configuration distance but you do not want to be hitting the mechanical limits. The travel can be increased until you get close to the mechanical limits and/or your Z carriage with extending dust collection is close to hitting the Y rails.
If you change your C3D recommended settings you should write them down so later you can reenter them when upgrading CM. Everytime you upgrade or reinstall CM you need to send the configuration to configure your Shapeoko but more importantly configure CM.