torque converter builders

so, this may be a dumb question, but at what RPM do I want it to stall?
I mean, what happens there ?
peak torque?

Thats for your converter company of choice to determine based on the info you give them. They will want to know your weight, final drive gear, tire size, power output, intended use, and probably the most important number your cam's duration at .050. Have all of this info in any email or phone call you have with a converter builder.