30 inch pounds means that the machine has enough torque to move a one pound force around at a distance of 30 inches. Applying moments (force x distance), this means at a radius of 5 inches, the motor is capable of moving 6 pounds around, a 4 inch radius would move 7.5 pounds.
I think that the motor could be capable of doing the job. If the paddle was not a solid plate, but fingered, then even less load would be moved. But, I have never tried to stir half a gallon of plastic!
I would be thinking about the speed, is one rev per second too fast. What speed do others use.
I respect Dels input, he deals with motors and real engineering on a daily basis, whereas I deal in theory. But you now have all the facts. If the motor is really cheap, it could be worth a try.