^There were no q's in that post...

Anyway, 2 things. First, petco and petsmart underfeed their snakes. I wouldnt trust them for feeding advice.

Second, it should be a litter larger than the widest part, but you're in the ball park. A size up wont hurt him though.

It should be eating mice roughly 12-18 grams based on the 10-15% rule