Nope - that you'll have to deal with yourself.. not sure what specific pin changes would have been neccesary, since the pins for the X3 are defined by making sure you set the motherboard correctly in configuration.h . If you changed them, then either you werent running a standard configured X3, or you altered something else non-standard or used a very old marlin as your starting base.... But the X3 is fully supported with just a configuration.h setting under Motherboard_Type.... *shrug*
But obviously, if you've rewritten bits of the source code you have now for whatever reason, then yes, you will need to repeat that on the new source code folder.. this is why its important to not change things unless you absoloutely have to as you then become locked into your modified firmware and not the 'standard' 'mainline' firmware....