Good evening Genie @tigereyes2004. It sounds like you have made a decision that takes into account your age (73) and your current physical condition. My life at or around 73 seemed to present the same dilemma. I had a major fall down a mountain and my right shoulder had not responded to two surgical attempts. The only option was a reverse shoulder replacement. The pain I dealt with daily was not responsive to acupuncture, physical therapy, or medication. So with my surgeon's loyal support, I underwent the reverse shoulder replacement. The surgery was done well. I received excellent post-surgical care and physical therapy. After spending a year in pain, I was thrilled to be pain-free once again. My enthusiasm for my business, my friends, and my friendly pets came back easily and I just remember being happy every morning.

You may not have discovered this recent news. It is now possible to custom-make the shoulder replacement mechanism the same way they create the knee mechanics. That should make a lot of difference. Mine was the best choice at the time. So technological advancement has made that surgery more accurate.

Your other concern is neck fusion. About two years later I began to have pain and numbness in the shoulder replacement arm. Come to find out it was a neck issue and both surgeons supported a fusion surgery. That one wasn't the easiest surgery I have been through, predominantly because of the rather uncomfortable neck brace I had to wear for three months.
However, I have absolutely no pain or discomfort and good ROM as long as I do my neck exercises.

Now I am 81. At this age with SFN (small fiber neuropathy) complete with pain and strain........I, like you, would not want to spend a considerable length of time in post-surgical recovery. So....I think I can see both sides of your situation.

Have you been able to see videos of the surgeries? That sure helped me understand what to expect. I don't have the reverse shoulder images. However, I will attach the neck fusion results.

May you be safe, free, and protected from inner and outer harm.
Chris