I've been told polishing any chamber that may take a heavy load is a very bad idea. The brass no longer "grabs" the chamber wall and can cause higher pressures and/or blown cases.
Instead of buying a hone, try a chamber filling brush with a patch saturated with JB Bore paste. Put it in a battery powered drill and then give it hell.
As far as cutting a new forcing cone on one, S&Ws come with a 5 degree forcing cone I believe. They say an 11 degree throat is better overall. Some people even go to an 18 degree forcing cone but that is a bit much.
You need the plug gauge to make sure you don't over cut one. If you do, your accuracy may go down the tubes.
Personally, I use a Lewis lead remover on my revolver forcing cones ever so often so any wear on the cone doesn't build up to let the cone split like so many are supposed to do on the 357 K frames.
Just my thoughts and worth what you paid for them.