It doesn't look like there's a universal joint at the back end so you won't be moving it in any direction enough to make any difference. Just go for the smoothest possible operation and be happy. Also I'm going to assume you know that your prop is on the wrong way to work as a pusher.....

If the motor itself was back at the tail then you could make effective thrust line changes. Downthrust at the back is still downthrust since the idea is to pull or push the nose down to counter the natural tendency to climb as speed increases. Right thrust is a little different if you need it. On the nose you'd set up the motor with the right prop tip pulled back but on a pusher the right side prop tip would be pushed forward to get right thrust. The thrust line works like a rudder when it's at the tail.

There's no magic to setting up a pusher for thrust angles. Just look at it and imagine which way the offsetting will move the tail. If it helps think of the motor being turned to 90 degrees in any given direction and what THAT will do to movement at the tail. Obviously you wouldn't use that much or anywhere near it but as a visualization aid it should help.

Also good luck on getting that long a shaft to operate without a lot of wobble and slap. Or drag in this case since if it flexes due to prop issues the shaft will rub on the foam. I foresee some melted foam in your future. The motor and prop would run MUCH MUCH smoother if you mounted the motor at the rear with very little extension to the prop. Long shafts that are rigidly mounted at the ends are not good options for power transfer when run at high speeds with slender shafts and big flyweights at the end.