Personally I do a great deal of "torch" heat treating. I come at from a bit different angle then some, as I tend to do a lot of differential heat treating. I achieve this by using a "imiter plate" in my quench tank. Its a simple piece of 1/4" aluminum plate, chocked full of 3/8" holes, with each corner having a 1/4-20 threaded hole that has 4" carriage bolt in it. This allows me to "set" the depth of the plates surface below the surface of the quench oil (generally 1/3-3/4 of the blades width that I'm quenching...depending on the given blade and it's intended use). I far prefer this method of being able to control just how much of the blade hardenes versus doing a "soft back draw" simply because for me its a much easier and surer method to achieve my goal(s). Also, having tested a large number of JS applicants over the years, I can tell you that roughly 80% who chose to use the "soft back draw" method (fully harden the blade, then TRY to draw back the spine) failed their performance test(s).
It might be the fact that I've had many years of practice with the torch heat treating method, but I personally feel that I have far more control over the heat when using a torch versus using the forge. With a little practice, you can almost "paint" the heat on a blade. And I far prefer either of those methods to a heat treat oven for carbon/plain steels.
Your going to want to go slightly above non-magnetic. Generally austinizing temp occurs approx. 150-200F above non-magnetic on most carbon/plain steels. Keep in mind that in order for carbon/plain steels to harden, you want to at the steels austinizing temp WHEN IT HITS THE QUENCH, meaning that you need to be SLIGHTLY above when the blade is removed from the heat (the blade is going to loose heat between the time you remove the heat, and it hits the quench). As quenched hardness for the steels you mentioned should be in the low 60s. Personally, for a "chopper" and for the geometry/grinds I use, 56-58 Rc is the "sweet spot" for the steels you mentioned.
