I am an IT manager for a government agency in Illinois. If someone internally was qualified you most likely would not have received an interview go into this interview with your eyes wide open. Accentuate any practical experience you have and be prepared to a answer those touchy feely questions leaning toward liking to work on a team, being a self learner that doesn’t need hand holding, paying attention to chain of command issues and literally relax relax relax. Never let them think you are sweating. Good luck, I think you have a real shot here. Make sure to mention your performance awards it does make a difference. I do hiring interviews all the time so am not blowing smoke up your rear end. Go for it!