New to gassers and getting ready to install my first on a big flat bottom wing trainer. The engine is a G26. Help????

What plane is it? Most big planes have the right and down built into the firewall these days. If you have to add some right and down, I would think no more than 2 or 3 degrees for both would do just fine.

The plane is a treehopper. I shortened the nose to handle the weight of the gasser. This way I would not have to add tail weight. The fire wall looks like it mounted flat. Thanks

THREE DEGREES RIGHT AND 1 DEGREE DOWN FOR A FLAT BOTTOM WING

What would be a good solution to set the degrees without an instrument to do so?

MOVE THE ENGINE OVER RIGHT OF CENTER 1/4 INCH AND SHIM SO THE SPINNER IS CENTERED WHEN THE COWL IS ON.AS FAR AS THE DOWN THRUST DON'T REALLY WORRY ABOUT IT UNLESS YOU HAVE A CLIMBING PROBLEM WHEN THE THROTTLE ON 3/4 OR MORE.A FLAT BOTTOM WING LIKES TO CLIMB WHEN THERE IS TOO MUCH SPEED,DEVELOPS ALOT OF LIFT.WITH THE SHORTR NOSE THE RIGHT HAND THRUST IS REALLY WHAT YOU WILL NEED SO GO 1/4 ON THAT

3dd
Go a 1/4 what? Inch or degree. This plane is a box or stick type, no cowl. When moving the engine over a 1/4 inch is that facing the nose or in the drivers seat?