Most people use steel washers around the mounting bolts to cock the mount or the engine on the mount?
Also Ernst makes thrust angle shims in 1, 2, & 3 degree sizes.
http://www2.towerhobbies.com/cgi-bin...?&I=LXE952&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXE953&P=7
Enjoy,
Jim