Can you help me with this assignment? Thank you!!

If you need a measure for your variable assessing political identification for your study including 18-25 year old emerging adults across social economic status, and all you can find assessing that construct is an assessment on political identification that was written and tested on a sample including a well-educated group of 50s+: Is it better to design an entirely new one or to adapt the valid reliable one that already exists, albeit for the wrong population? What would be needed if you were to tailor the measure?