I will let you know what I think tomorrow, I have a guy putting the HEI in my 72' as we speak. He is also going to re-jet the carb and get that dialed in 

packs a pretty good punch 
I've been thinking about doing this too. My coil wire in my EZ-Wiring kit is tiny. Like 16 or something.Don't use the original power wire for the new HEI -- the original has a resistor along the way and the HEI won't get full power.
Strictly speaking, I'd run a nice thick wire (say, #10) to the battery, with a relay to the fusebox (something that's hot in crank and run, of course) to get maximum voltage to the new dizzy.
-- A
Best upgrade yet