Conformed to the Image of His Son

What does Paul mean when in Romans 8:29 he speaks of being "conformed to the image of his Son"? Is it a moral or spiritual or sanctifying conformity to Christ, or to his suffering, or does it point to an eschatological transformation into radiant glory? Haley Goranson Jacob points out that the key lies in the meaning of "glory" in Paul's biblical-theological perspective and in how he uses the language of glory in Romans.