Two such opposite people shouldn't get along as well as you two will. But you will get along well. In fact, each of you will derive a lot of benefits from the other's way of doing things.
If there's any tension generated by your differences, it should be a creative type of tension that will actually further your purposes. Your friend will bring their spontaneous, high-flying creativity to the table, and you'll bring your sensible, levelheaded approach to any problem. You'll be able to blend your strengths into one. This friend will be able to jostle you out of any rigidity with their spontaneity and enthusiasm for life. In return, you'll ground their sometimes off-the-wall ideas.