Do you have a drumb sander or grinder on a dremmel??? Just a thought. How much thrust do you have when you remove the washers?? How far over to the left does the mount have to move before the crank is centered and does that give you any right thrust?? Is the fire wall already premade to give you a set thrust angle? Can you grind down the motor mount??
If you build a kit plane sometimes you have to think a little outside the box. On some kits the thrust angle is already set when you mount the fire wall into the fuse sides so you just have to center the crank by moving the mount/engine a bit to the left.
Check your instructions and plans to see if this is already done for you. It doesn't hurt to trim down the motor mount of the inside of the cowl to get some room.