The resistor was usually mounted to the firewall about valve cover height or slightly above where it could get good airflow for cooling. Any resistor develops some heat- - - -that's why the housing is ceramic, to protect nearby parts from heat damage.
If there was not a good reason for running a low-resistance primary winding in the coil for producing a hot spark during cranking, would GM have gone to the effort and expense of designing their ignition systems that way? I can't think of any manufacturer of any product that will choose to make their product more complex and expensive than necessary, and then produce millions of that product. Just because a few self-appointed experts have declared themselves to be more intelligent than the General Motors design engineering department doesn't seem to be a good reason for me to ignore 50-something years of experience working with these vehicles. "Your mileage may vary".
Jerry
