I'm with midas. Even with good intentions, Chicago Barbecue (and for the record, I love Smoque's brisket) is going to fall short of your Texas friend's expectations. Instead, if you're going to insist on taking him for Barbecue, instead of say, Chicago style pizza, hot dogs, or Italian beef, I would take him to a place that serves a product that represents the best of what would be considered Chicago style Barbecue and make no apologies for it.
A joint with an "aquarium" smoker that puts out rib tips and hot links (distinctly different from a Texas style sausage) would be your best bet. The consensus of opinion round these parts is that the best places serving that type of 'Que are, in no particular order, Lem's, Uncle John's, and Barbara Ann's; all on the south side, and Honey 1 up on the north side.
Hope you have a great dinner together,
Buddy