1 hour 10 min. is not much - however, you can make it with some luck.
I recently passed through MIA immigration in less than 2 minutes (no lines, less passenger). Waited for baggage 10 to 15 min., customs 10 seconds. Then deliver your baggage to the AA desk at arrival behind customs.
I always like to sit in front of the plane; sitting in the last row could mean another 3 to 5 minutes!