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！
カナダ 
