The equation is Ohms law, I = V/R. Without dwell control, using points or Pertronix, the coil is charged after a few milli seconds and the current is only limited by the series resistance of the circuit. This is the sum of the coil resistance , and ballast resistance. The V, is the supply voltage, I used 14V.
The HEI you use has a means of active dwell control, by controlling the coil charge interval at medium and high speeds, and a low speeds, a current limit by using the power switch in a linear mode. No ballast is required, for HEI.