42L, BMI 40. Too Obese for Breast Reduction?

Your risks of infection, bleeding, wound healing problems, ckot firmation, etc are higher. You must make this informed risk.

Without examining you and evaluating your medical record, it is impossible to tell if you are a good candidate for surgery.  If you post pictures and give a more detailed medical history then we may be able to give you more specific advice.   Good luck.