At that time in the morning, you will likely be the only flight processing through immigration; unfortunately that probably means they have less people manning the immigration booths at that time. If you're at the front of the plane, immigration will be a snap (10-15 minutes tops), but if you're seated towards the back and the endpoint is GUA, the line could be longer (25-30 minutes). If you are somehow behind some other LAX flight, expect at leats 30 minutes.

Having said all that you should be able to make the first flight out. You need less prep time for the domestic flight to Flores so even budgeting a worst case of an hour, you will make it to the Taca counter with at least an hour to spare. No problem. If something happend Taca will bump you cak to the next flight.