Google reveals a "
Jun Horie" who is an architect in Hiroshima. Probably not old enough to be your uncle, though.
How sure are you of his name? Do you know how the first name is written?
There is an architect in Hiroshima by the family name of Horie, born in 1933 with his own firm since 1966.
I would suggest
contacting him and asking his advice. He may be a distant relative, or at least ought to have a better line on tracking down fellow architects in the area than we would.