It's been almost 80 years since Word War II ended, but we still have customs that have been around since before the war in Japan.
この場合、次のような言い方ができます。
ーIt's been almost 80 years since Word War II ended, but we still have customs that have been around since before the war in Japan.
「戦後（第二次世界大戦が終わって）もうすぐ80年経つのに、日本では戦前からの習慣がまだ残っている」
It's been almost ○ years since ... で「…以来、もうすぐ◯年になる」
we still have customs that have been around since ... で「…からずっとある習慣がまだ残っている」
ご参考まで！
Even though it’s been about 80 years since the war ended, pre-war customs still remain.
It's been almost 80 years since World War II, yet some pre-war traditions still persist.
「戦後（第二次世界大戦後）」は英語で since the end of the war や since World War II ended と表現します。
「〜のに（意外性や矛盾）」を出すには、文頭に Even though を使うのがぴったりです。
Even though it’s been about 80 years since the war ended, pre-war customs still remain. （戦後約80年も経っているのに、戦前の慣習がまだ残っています。）
カナダ 
アメリカ合衆国 
