ORIGINAL: vasek
If i understand your problem you have mounted the wings fist & you're measuring distances between the "extremities" of wing-stab to line up the stab?
If that's the case you should be mounting the stab fist & align/ mount the wing afterwards.
Hope this helps
If you make certain the wing is centered and straight with the fuse, you will have no problem in mounting the wing first. What Kit is this? Bolt on wing or Rubber banded? A picture or even a MS "Paint" sketch would help ailot in identifying the problem.