If your doctor is suggesting you take 8 Tylenol's a day, i would begin searching for a new doctor. Tylenol will cause more damage in the long run than the morphine would, IMHO.
Personally I don't think 8 or even 12 Tylenol would provide you with enough pain relief if you normally take morphine. Maybe there is another pain med you could try?? I was allergic to morphine so I was switched a couple times until I found what worked for me. I hope you find something that works for you. I would suggest bring in a printed list of meds that's covered.