An elevator will move corn alright if you keep it fairly flat. Which it would be loading a truck. I used one for years out of several bins that only had 6 inch unload augers. The elevator would keep up with the six inch auger.
Just keep the chain tight and do not over load the paddles. Some corn will be rolling over the top to the next paddle but you do not want a lot of it doing it. IF you have a lose chain or over load it the chain can ride up on the corn and then break. Then you have a mess.
As for the 1 hp motor working that maybe a little slow but I would try it. I had a 1 1/2 motor on mine and it worked fine.
The wider the elevator the more corn it will move. I had a JD 350 elevator that would move shelled corn very well. I had a narrower NH elevator and it did not move it very well. The shape of the paddles make a difference.
Make sure any screen sections are covered on your elevator. Most elevators where made for ear corn. They wanted the shelled corn separated out. So there would be a section with a screen/slots that would let the shelled corn fall out. If yours has this screen/slots and you do not have the correct cover I have just bolted a piece of plywood over that section.