Every time I have ever tried to operate my gun with my weak hand the hardest thing to get over is not the operation or the actual shooting, in honesty, it's just the awkward feel that it's just in the wrong hand.
My eye goes where it needs to go, my sights line up nice, my fingers do all of the right moving and I can operate every part of my gun just fine (though I could practice more to make it a little faster) but sometimes just getting one good solid and comfortable grip is the hardest thing for me to conquer. So, I started just playing with it with my weak hand.
Watching TV with it empty in my lap and fingering it and holding it and working it with my left hand. Training my brain to accept it just as readily in my left hand as in my right.
That's my only suggestion.
Nothing much to add for carry method but I certainly hope your surgery goes well and is successful. Good luck and let us know.
