I was in GUA yesterday. If you have all your boarding passes already, it really is not a problem, just walk from one gate to another, no security to go through. The works might have progressed, planes are not tugged to their gates, so my flights were on time, 1hr20 seems like plenty of time.

Now if you have to re-check in or have luggage that needs to be re-checked in, 1hr20 is very short, so check that CO and TACA interline, and double check that TACA took your luggage before you board flight #2. Check, check, check...

Booze and cigarettes are pretty cheap at the duty free shop if you have time, and if it is open...