Good luck.
For widgeon: Generally twin engine helicopters will consume less fuel OEI than both engines operating, therefore you can generally go further OEI than twin engine, albiet at a much reduced IAS. This changes when considering wind. As best range speed increases when facing headwinds, there is sometimes a critical wind speed that will determine if OEI has better range than twin. For example, the B212 will cruise further OEI than twin engine until you face more than about 35 to 40 kts headwind. I believe this speed is fairly close to most other twins.
The 902 is full cat A OEI so even at max TOW he should have a high OEI drift down height and be able to fly further than he would have with both engines, wind aside.