Rotated object, now firing wrong way

I was using a basic cube as my spaceship in my game, but now I've found a free model online, and I'd like to use it, but it requires rotation for it to face the right way. Unfortunately, now the ship fires the wrong way, and "left" makes it go right and vice versa. How do I correct this?

My original cube has no rotation, and it fires up along the y-axis. When I imported the model, I had to rotate it 90 degrees on the x-axis and 180 degrees on the z-axis.

Ideally rotate the object in a 3D app so it's appropriate for Unity. Otherwise, change the directions in your code as necessary.