There are plenty of places to mount a resistor other than the firewall. Just put it somewhere it will be in the airflow from the fan to keep it cool. I've seen resistors attached to the same bracket that holds the coil onto the side of the engine.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!