2.5 feet is a decent sized Paleosuchus, and the size of the rat being fed is a needed for an adequate answer. Rat pinks, fuzzz, weanouts, adults, burnt-out breeders.....each size inserted into your post changes the answer dramatically.

Personally, I would rather obtain a nice, healthy, well fed animal, as you know it will refuse food while it acclimates to its new home, especially in view of its size.