The S-76B, being no longer in production, is a fine machine but support has to be somewhat suspect. Having flown A++ and C for SAR and Casevac and the B and C+ for corporate work, I suggest you find out how long a replacement main gearbox will take to arrive. The big problem I see with the B model is the higher basic weight (how heavy will your internal fit be?) and the higher fuel burn. All things taken into consideration, sadly it might not have the long "legs" you need.