Need help - modifying a face to fit complex curvature

[PALASH001FQ9LJ]

Hello! 

I'm designing an air splitter of sorts for a project of mine, and i need my outlet nozzle collar (highlighted in red) to sit flush with the cylindrical curvature of the inner main body (highlighted in blue)! Does anyone have an idea how to go about achieving this? Thank you!! any help is appreciated 

[davebYYPCU]

Not completely clear, but I think it would be Extrude the red face to object blue face.

Might help...