Amazon.com Inc. is shopping for used long-range Boeing Co. and Airbus SE cargo planes, according to people familiar with the matter, the latest evidence of the e-commerce giant’s ambitions to move products across borders itself. Amazon is in the market for refurbished cargo versions of one of the largest twin-engine passenger jets currently flying, Boeing’s 777-300ER, along with conversions of Airbus’s popular A330-300 wide-body aircraft, said the people, who requested anonymity to discuss confidential matters. Both models are a step up from the mid-size Boeing 767 aircraft that have served as the backbone of Amazon’s fleet for five years. Converted...