Editing Chevy 350 TBI running hot

I have a chevy s10 with a 350 TBI motor and a 700R4 Transmission... it is really fun to drive but i seem to be having a cooling issue. I just replaced the thermostat with a 160 degree unit and upper rad hose which helped out alot but after a few hours or so of drivin the temp gauge starts going up to the red zone. NOw i do have a twin fan system on the rad also that i manually swith on before i start the motor....Any ideas?