First, it might be a good idea to turn the distributor body about 90° CW to get the vacuum advance closer to where it is supposed to be. Looks like it's hitting the carb, or is pretty close to. Then follow krazykuda's instructions.
The only way to get it adjusted to 90 degrees is remove the distributor and move the sprocket 90 degrees. I tried to move it 180 degrees and the vacuum advance was in a worse position that where it draff