IF - you can check your luggage through you could MAYBE pull this off, but I am doubting you can do that because GUA is not really a hub where people make connections. Most flights simply start or stop here.

When you get off the plane in GUA there is no seperate goto Customs containment area (at least a few weeks ago, the airport is under construction) you just go thought the general terminal area upto where people enter from the security checkpoint, hang a left and go down stairs to Immigration, and then baggage claim and then head outside.

With 1:20 I am pretty much thinking you are screwed either way as depending upon which side of the terminal you are in, they tug in the planes since there is no charts yet for the taxi ways and construction, and I normally figure at least 1 hour from wheels down to being out the door if you have to reclaim your bag. They have a big belt but just 2-3 carts and on tractor that they are switching out.

Down here we call this a Fijese - I would change to a later flight.