Importance of thrust line!
For stand off scale and the average Sunday type flier the thrust line being off by 3/4 of an inch will not be a problem. If however you are dealing with an aerobatic aircraft or race type plane changing the thrust line could have negative results for top performance.
You are far better off not changing the thrust line at all. You do not indicate what airplane you have so it is a bit difficult to give you a clear idea what your best options are