RE: Engine Mount Angle Help....
Down and Right Thrust is often required to correct flight tendancies in planes. The forces on a plane in flight are NOT symetric, so without right and down thrust the plane will fly poorly or incorrectly.
Thrust angles are given in degrees, and expressed as the angle difference from perpendicular to the fuselage chord line, when viewed from a PILOT's perspective ( NOT from the front of the plane! )
So most planes have SOME right thrust and often a bit of down thrust. NEVER "left" thrust... unless the engine spins BACKWARDS.
Usually the proper amount is already built into the firewall, so all you have to worry about is getting your engine mounted squarely to the firewall.