The KingAir C90A is one of the types that I fly occasionally. At sea level, the torque would go well above 1315 if you pushed the power levers to the stop, so you must be careful to set no more than 1315. The torque does rise noticeably when the rpm is reduced, and the amount of rise you mention is probably roughly correct. When reducing from take-off power to climb power, the first step is to pull back the power levers to reduce the torque to around 1000. Then reduce the rpm, which will cause the tongue to rise, and then adjust the power levers to set 1315 torque.
if the air temperature is well above standard, you may hit the 695 degree ITT limit before you reach 1315 torque, so you must watch that too - i.e. set 1315 torque or 695 ITT, whichever you reach first. On some aircraft, at higher altitude, the 101.5% gas generator speed limit will come into play before hitting either the torque or ITT limit.