Stuart I kind of agree with you on the wire capacity. MSD mention under what condition the coil draws the most, but I couldn't find it again. I find that MSD makes an HEI coil that draws 20 amps;

http://www.msdignition.com/dist_82.htm

My experience has been that the larger wire needs to go all the way to the ignition switch. When I originally installed the HEI in my truck, I didn't go to the switch, only to the fire wall. 8-( I drove that way for 5 years. I installed my rebuilt 292 the wire from the firewall to the switch smoked in less than 300 miles, why?? more compression? evidently something caused the HEI to draw more.

The 10awg will barely fit in the factory .250 tabs, so I usually solder them as well.

Larry

I don't own a vehicle that isn't old enough to drink.