If he's 650 grams he needs to eat 2 to 3 ADULT MICE.

Or a small rat. Either one I'd be looking for a total prey weight of around 50 to 70 grams. Like said above. Find the widest part of your snakes belly. And get a rat whose hips are the same width. If the mouse you fed him was as big as his neck right behind his head. That's like you starving and going in to the kitchen and eating 1 potato chip. Haha

My male is 500 grams and capable of taking a small rat down. He's on weaned rats though weighing 40 grams or so.

Ill move him up to small rats here in a week or two.

Hope this helps.