My 2 cents. I was in a similar situation a year ago. I had been out of flying for 5 years. I was hired by a 135 operator and sent to school immediately for Gulfstream.
I struggled through four of my seven sims both with regaining my scan and situational awareness. I managed to pass my checkride but I was seriously scared to death when I walked in to the Sim that day.
If I could offer some advice, I would go find a local Sim trainer at local flight school and do a minimum of 10-15 hours shooting approaches conducting sids and stars plus regaining your scan and situational awareness. This allows you to concentrate on learning the aircraft and making the most out of your Sim training. After I got to the aircraft I spent at least 30 more hours continuing to improve my scan and situational awareness and finally joining my counterpart in the cockpit instead of hanging onto the tail.
A good read for improving basic aviation knowledge is "Everything Explained for professional Aviator" I installed it on my iPad and take it with me everywhere. It's good info and also good to put me to sleep.
I wish you guys the best of luck. I truly feel coming back is the best decision I have made in my life. I currently have a job offer with Frontier Airlines. Don't waste too much time down in the regionals or with the 135 operators do a year and then move onto the majors.