Just wondering why you feel the need to switch over to rats so soon? Your snakes at 235-245g are not very big and two mice at that size should be fine. Why not try and switch them over to F/T mice while they are still eating mice and then switch over to F/T rats in the near future? My snake was about 800g before I switched him over to small rats (40g or so) and up until then he was getting 2 adult mice a week. He is now around 1200g and is getting one 70-80g rat a week which is where I plan to stay for the time being.