Steve, the large yellow Accel coil has a very low primary resistance. The important parameter here is the current. Shoot for ~3 amps with points and you will be OK. Greater than 4 and point life really suffers. I am using two series 1.5 ohm ballast resistors in a 24V system.
Jon, the reason that the primary resistance is lower is that the primary inductance is also lower. A lower primary inductance will result in quicker saturation which is needed for the shorter dwell times in 8 cylinder engines and/or high rpm.
