If you are now a senior manager, you have probaly learned now that you should be able to effectively work with anyone whether you like them or not. However, your former boss is likely to be fairly unhappy at this development. You may need to havea plan in your back pocket of where he could be moved to if he does not want to work with you.
You need to sit down with immediately and talk about what you expect of him, why you are retaining him on the team and how the new relationship will work. Acknowledge any problems you had in the past and how you contributed to them and what you have learned since then.
It may be possible to salvage this relationship if he is willing to try, but if his attitude is negative at the end of this talk or if he after the talk starts making public problems for you, then get rid of him as soon as you can. This does not necessarily mean fire him, if there is somewhere he can transfer to to save face, that is fine.
His talents may be good but they are useless with a bad attitude. He needs to be aware that you are willing to restart the relationship and that you respect his abilities, but he also needs to realize that his own attitude will dictate if he can keep his job. Don't keep him if he is a snake in the grass. The problems he will create will far exceed any technical abilites he can bring to the group. The choice in the end is his, can he get along with you or not.
I've seen this play out several times at work and it it all came down to the attitude of the employee. If he was willing to work for someone who used to work for him and who he disliked at that time, it will work out fine, but if he isn't the best thing for you, for your team, for the project and ultimately for him is to move him elsewhere in the organization or fire him as soon as possible.