Another look through the T-45C NATOPS shows a level flight speed at 30,000' of Mach .85 for a Goshawk. I've personally seen 450 kts IAS at 14,000' at MRT so that might be a good reference number for getting airspeeds for the model in line with the real aircraft.
Generally, we climb out at MRT at 250 kts IAS to 10,000' (intial rate of climb is ~6500 ft per minute) then accelerate to 300 kts IAS the rest of the climb. If we're going high enough we'll actually continue the 300 kt climb to intercept Mach .76 but I've honestly never had to do that (don't generally cruise above 30,000' where it might be an issue although the T-45C can cruise up to 41,000').
Normal cruise is ~1200lbs/hr on the fuel flow gauge for about 320-330 kts indicated (TAS is alt dependent obviously). The cruise fuel flows are based on altitude to achieve the best ecnomoy and range, the lower you are the higher the required fuel flow and vice versa. Another thing about training command aircraft is that no two seem to fly exactly the same so that might be a consideration. I've flown jets that need 1500 lbs/hr to maintain 250 kts IAS and others that only needed 1200 lbs/hr for 250 kts at our normal training altitudes of 14,000-18,000 ft. Somewhere, I had gouge FF settings for the simulator for various altitudes and the resultant IAS but it's location escapes me at the moment. If I find it I'll post some more numbers that might be of use for getting the model really accurate.
Lastly, I saw some discussion about the T-45C AoA gauge. For on-speed we are at 17 units AoA which is the 3 o'clock position on the gauge. Unit's is an arbitrary measurment calculated to set the proper nose attitude of the aircraft so the tail hook is in an optimum location to catch a wire (obviously is also in the flight regime where the aircraft is easliy controlable at this low airspeed). Early on optimum AoA for on-speed in the Goshawk was set too high and there were some issues catching wires until the problem was identified and the numbers changed because the nose was too low and the hook too high.
Stretch