YOU SAID:

If I had feet I would stand on my head

INTO JAPANESE

私は私の頭に立って足を持っていた場合

BACK INTO ENGLISH

If I stood on my head and feet had

INTO JAPANESE

私は私の頭と足で立っていた場合があった

BACK INTO ENGLISH

When I was standing on my head and feet

INTO JAPANESE

私は私の頭と足で立っていたとき

BACK INTO ENGLISH

When I was standing on my head and feet