Eating too much???

I have lots of snakes that will eat rats or mice. They could care less. Although I hear that some prefer one or the other.

3 years old would make it an 04 or an 05. 700 grams with a full belly sounds pretty light for that age. He was probably underfed with its previous owners. I would feed it as much as it wants once per week.

the petstore in my area is a NIGHTMARE and they barely ever have what i need. my snake will eat either rats or mice... but i find that he can kill a small rat MUCH quicker than he can kill smaller prey (we're talkin less than 45 seconds dead on the rat, and sometimes a minute and a half to 2 minz to kill mice!) i think it's because small rats are the correct size to feed him. it DEFINITELY makes life easier when you don't have to feed 4 mice at a time... one week the store didn't even have mice so i had to feed my snake 5 (FIVEEEE it was sad lol...) baby rat pups. he pounded them down but i could tell he was EXHAUSTED afterwards. (i compare it like this... 5 rat pups = like, a box of chicken nuggets... the small rat? haha... = a big mac ;) ) the week after that i finally finally got a small rat and i could tell he was much happier. he did kinda snake around thinking he was going to get more than one, but when he realized how FULL he was, he chilled his beans and went back in his hide.

thats my experience :P hope this helps!