Answer: Aren't trees amazing! I see two possible problems with doing this, the first being that sawing off a substantial portion of the original top at the trunk will create a huge opportunity for insects and disease to enter the trunk; the second being that moving the trunk further (by propping it up) may just break the last surviving critical roots that have kept it alive this far. It will also take years to reform the tree even if it is successful. Having said that, if the tree is really unacceptable the way it is then it's worth a try!
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