If you don't think he'll agree, take it through the Courts. Personally, any agreement you all can come to (if you can come to one) should be signed, notarized, and through the Courts anyway. But, if you need to take it to Court, ask for home evaluations. You may have to pay for it, though, so be prepared for that. You can ask for supervised visitation for your son, but you'll need to PROVE abuse/neglect.
Is the job you're referring to a potential job, or is it a definite thing? Also, while the house is stable, the fact is that it isn't a "guarantee" because in the Court's eyes, there's no guarantee of the relationship lasting, which could lead to uprooting your son again. So, they may not even consider that aspect of the move. The job, they would probably consider, since it could lead to a better life for your son.
Is the job you're referring to a potential job, or is it a definite thing? Also, while the house is stable, the fact is that it isn't a "guarantee" because in the Court's eyes, there's no guarantee of the relationship lasting, which could lead to uprooting your son again. So, they may not even consider that aspect of the move. The job, they would probably consider, since it could lead to a better life for your son.