Opinion on a Rescue (don't have him yet, still deciding)

[Gocntry]

Personally, I had no trouble switching my bp over to rats when he was little, although this may be different because Monty is big, but I did just switch my guy over to f/t no problem. He doesn't even care if it is warm or not. I just have to show him that the rat is in there and then leave it and he crawls out and eats it.

I can say all the other rescues / adoptee's I have taken in went right to f/t rats no issues, or f/t mouse with my Corn.
But between my Corn and Boa I'm sure those guys would eat whatever I had on hand, They like FOOD

and I had no clue what they were being fed before, adopting a snake third hand you get little info on them usually.

I just wondered about Monty because of his age and they were very specific on his eating needs

[Bogertophis]

Young BPs are usually more "open-minded" about prey (mice or rats) than adults are; I would have been every bit as skeptical as you were about Monty, with the info given.
Anyway, I hope he got a good home now & does well for his new owner.