I would have definitely suggested going over there and spending some time with her cat and Safari at her house beforehand while sort of having Safari "quarantined". You don't want to give Safari the run of Shrimp's territory or it could cause him a lot of unnecessary stress, especially being he is an older cat. I know you don't have too much time before you leave at this point but if she is close by you should take the time to go visit and do a brief introduction before you drop Safari off. This is what we made sure to do with Echoplexia who will be watching our cats when we leave for our week long cruise in December. =) We gave them a play date so that they were not ENTIRELY strange to each other while Bauer and Dex stay there and their smells are throughout her place and on her and her boyfriend.
If at all possible I think it may actually be a better idea to keep them in separate quarters while Safari is visiting, while she still makes sure to give Safari plenty of attention. I think it's good to have an intro or two and maybe supervised visits (lol the way that sounds) so that they are well aware that one another exists, but like I mentioned before, Safari and all of his rambunctiousness (is that even a word?) may be too much for Shrimp to handle on a constant basis and it may become far too overwhelming for him; which wouldn't be very fair because it is HIS home.
Maybe give both boys lots of treats when they ARE around one another so they can associate playing nice with goodies!
Speaking of association and positive reinforcement, I know it may sound mean, but if she leaves Safari in the room and does not go into him every time he cries he WILL eventually get over it and quiet down more than likely. Perhaps if she has a spare room in her house with a bed she can even go sleep in there with him at night and keep him down if you are concerned with him sleeping alone and becoming lonely? If this is not possible though you definitely do not want her to cause him to associate his crying with getting attention or she will have one hell of a week on her hands.
Hope this helps, and that you enjoy your cruise! Can't wait for ours!