I have a 1400+ centimorgan Match to a great uncle on my father's side. Is it common to have this strong of a match to a great uncle? I have read this high number is usually shared with half-siblings, not relatives 30+ years my senior.
According to the Shared cM Project, it is unlikely but possible that he is your great-uncle. The 95th percentile range for such a relationship is 619-1159 cM, but the 99th percentile range is 486-1761 cM, meaning it would not be unprecedented.
Your relation would be a little more likely to be an uncle/half-sibling, where he would be just outside the 95th percentile range (1435-2083 cM) but within the 99th percentile range (1294-2230 cM).
If I were you, I would (1) try seeing how closely he matches other common relatives and (2) investigate whether he could be related to you in multiple ways, such as if your most recent common ancestors were cousins of each other.
If you are from an endogamous population, that should also be taken into account.