We top out at smalls or small/mediums for even our biggest female BP who is slightly over 2,200 grams and still growing of course. Part of that is because we feed live so we don't want the snake facing down a large rat in a confined area, part of it is because we'd rather feed a couple of smalls and let the snake regulate what it does want to eat that week - if it's hungry it will take two, if it's not so hungry, it will just take the one and that's fine too.

Think of it this way, in the wild these creatures do not have a weekly feeding schedule so yes they can take quite large prey because that's what wandered by when they were hungry so they nailed it. In a captive environment, they have weekly access to prey so they don't need that big volume all the time. BP's are very self-regulating so if you push bigger prey on them too much, they will simply stop eating for awhile. You just don't see obese BP's.

As far as sizes all I can say is my male BP who is 700+ grams isn't taking smalls yet and he's a good size for his age. He takes big fat weanlings that I raise myself, is gaining beautifully on that and has never refused a meal from the day he took his first one. The youngest BP I have that will take what I'd call a small small is over 2 years old (she weighs a healthy 1,100 grams+)

Personally I'd go with a range of fuzzies, pups and weanlings depending on what these snakes are used to and are already eating and their size. You can always feed multiples if you end up with a few too many smaller rats to use up. Since you don't want to offer them food right off after shipping, you've got time to set them up, check them size wise and put in an order. Back when we fed f/t we could place our order Monday morning and have it at the door frozen hard by Tuesday afternoon (we used www.themousefactory.com)

Go with a prey size about the size of the biggest girth of your snake or slightly less than girth. You want your snake well fed but there's no benefit to having a big distension/lump in your snake after feeding.