Hi,
I adopted my Chico, who is now almost 2 yrs old, last Thanksgiving. OMG the growling he did everytime my husband walked by was unbelievable. Not to me only to him. I talked and let him out every evening and all weekend with me. My husband continued to uncover him feed him first thing and talk to him. Chico prefers me but will go to my husband on his hand from me handing to him. He rarely growls at him anymore. It is all about you talking,socializing with him every opportunity you can always, offer treats to him, find out what foods hes likes and feed it to him. Chico loved pizza -most birds do lol. He needs to trust you. If you do this I don't see why he won't come around. It took Chico just a few weeks to be comfortable around me but my husband -still work in progress.
As far as your cage, My amazon's cage is alittle on the thin side so I always put Chico and Fig on playstands whenever I can - usually as soon as I walk in the door till I go to bed and all day when I am home on the weekends. Plus, easier to cleanup the mess! So just a suggestion to see if you can get a playstand. If he doesnt come on your hand to put back in cage, roll playstand over to the cage.
Hope this helps and hope you have a great experience with your grey.