There is not all that much steel at the frame.
look at the end of the barrel at the cylinder and you
will see what I mean.
A s/w 357m was sleaved because of the stupid 4 inch
12-6 crap.
I believe a model 66 , the forcing cone went to hell .
If you are going to do this, I would suggest stopping the
liner ( and drill ) before it reaches the chamber end of the barrel,
so as to keep the forcing cone intact.