As a surgeon who has operated on a number of men over 50 for gynecomastia, please allow some comments and observations.
First, the operation can be done successfully. Your skin, at age 50, has lost some of its elasticity -- as compared to a 20 year old. So it will not snap back as tight as you might want -- in fact you may still have a discernible infra-mammary fold (the fold under the breasts) after the operation -- but that can look normal on a 50 year old. I have never had any patient in whom the skin didn't tighten somewhat -- it is just that you cannot predict how much it will tighten. Of course, if you are or have been very overweight, the loss of elasticity is compounded and depending on the case, sometimes a skin excision is necessary.
As for healing in general, if you are healthy, nutritionally fit and follow your surgeon's directions (all assuming the operation went well in the first place), you should heal well.
For virtually all of my patients, one may return to sedentary work usually within 3-4 days after surgery.
Dr Jacobs