The Speedway method is excellent, but if the pins have been in the axles boss for all those years, they are not usually going to come out easy.
Suggest going to step #2, and remove the axle & spring from the car. Then you can put the assembly in a press. If you have a press, push the pins out from the bottom. Suggest using Kroil penetrating oil on the pins in the axle boss for several days before you press them out. 9 times out of ten, you will need to heat the axle boss, then let it cool completely for few hours before pressing the pins out. if no press, take it to a good machine shop and have them press them out. They can also install the new bushing in the spindles, and hone them to fit the new king pins. The combined BH & heat method could result in damage. Press is best.