Surgery complete! Transformed it from a men’s XXL to a fitted ladies T with gathered sides. Picked this up in August and only now got around to altering it.
Nifty trick for the gathered sides — used the discarded hems from another t-shirt project as the casing. Used my serger for all of the main work. Did a number of basting tries with the sewing machine before I finally said f*** it and took the plunge.