Oversized package on return flight?
 

If you are trying to bing back to US a package about 80 inches long but narrow about 15 inches and less than 50 lbs, how would you handle?

You don't state the 3rd dimension, but if it is under 20 inches you can check it as oversized baggage. All airlines have a max size of 115 inches/292 cm (total outside dimensions; length + width + height). Once you reach the US, if you have a connecting flight you will have to pay an oversize baggage charge (USD 100 on AA, it varies by airline). CX may or may not charge you (depends on your ticket and status).