YOU SAID:

I have no idea how long it was a good boy for the rest is up to you

INTO JAPANESE

私はどれくらいの間、良い男の子だったのか分からない

BACK INTO ENGLISH

I do not know how long he was a good boy

INTO JAPANESE

彼がどれくらいの年配の男の子だったのか分かりません

BACK INTO ENGLISH

I do not know how old he was an elderly boy

INTO JAPANESE

彼がどれほど年上の男の子か知りません

BACK INTO ENGLISH

I do not know how old he is an older boy

INTO JAPANESE

私は彼がどれほど年上の少年であるかはわかりません

BACK INTO ENGLISH

I do not know how old he is an older boy