Congrats on saving the little one. I would stay slow for a while (my personal opinion) if you induce regurge by feeding too large it would be way worse on an unhealthy snake. These guys can go a long time without food so keeping something on his stomach is going to be good for him anyways. I'd probably do a weaned rat next week and stick to those for about a month them bump up. He's still got a lot of life left so he'll be big before you know it.