Thanks for the comments. My idea is to turn the Ramps board into a CNC shield. The only problem at the moment is that GRBL is very focused on the Arduino Uno setup. So even though my library works with the Arduino Mega it is still not configured for the Ramps board.
https://github.com/Protoneer/GRBL-Arduino-Library has all the source code. 😉
(Github makes it so easy to share code and view it online.)