I have installed several profiles for GSX 777-300ER,
What do you mean, aircraft profile or airport profile?
You don't need a profile for the aircraft, regarding the stop position, if the gate was customized for a 737/A320, GSX will match the main exit of the 777 (L2) with the main exit of the aircraft used to customize the gate, hence the 777 being stopped too far away.
If the airport profile you use doesn't have heavy gates correctly customized for the 777, you just need to edit the stop position of the gate yourself.