Beside reversing the gear, you might want to save yourself a lot of frustration and open the bottom of the engine compartment up (removing the lip) so it is flush with the inside of the sides of the nose. A Dremel sanding drum works great for this, and it allows easier mounting of the engine/mount assembly to the engine mount runners.

Also, if you're using an OS 40 or 46, consider getting a Heavy Hub to put inside the spinner, or the proper size aluminum spinner to balance the model. I had to do this on two of these planes, with 3 different engines: OS .46 FX, OS .46 LA, and an OS .52 FS. Have fun... It's a great flying plane.