One other method to consider, regarding heating steel to a certain temperature, is "Tempilaq." This stuff is painted on the surface of the workpiece where it dries hard like paint. When the piece is heated (by whatever means) and reaches the desired temperature, the Tempilaq immediately melts, indicating a time to begin the cooling down process.
It's sold by Brownells and comes in a whole bunch of different temperature settings or grades. You just have to figure out how hot the particular steel you're working with has to get for good effect.