Hi bobd,
I had something similar to you and it took 14 months for the saliva and taste to return back to what I thought it was post surgery/ pre radiation. It varies greatly with every person. It also varies with how the taste buds/saliva glands react to the radiation. So there are many variables in play and no way anyone can tell you exactly when the mouth will return to its new normal.
On the feeding tube, you most likely have not used your mouth muscles and they have atrophied. A swallowing therapist can help you with that and I would recommend you ask your doctors right away if they have not already mentioned it. You need to get the mouth working again, even if food tastes bad.
Feel free to ask more questions. It helps because I have been where you are now. I however, did not have this board to help 4 years ago.
Take care and fight hard.
Jim