Thanks Keith!

Interesting, some of it's verbatim from the instructions that came with the FireCore distributor.
The important bit however would be this line:

"Coil primary resistance should be no lower than 1.4 Ohm"

That's the spec for an old points distributor, which also suggests the 0.7 Ohm Blaster 2 isn't that well suited.
Alot of coil manufacturers don't publish a data sheet, at least not online but what about the Pertronix FlameThrower?

http://www.summitracing.com/parts/pnx-40011/overview/

I've used Pertronix in the past and they're certainly a reputable enough company to buy from. How do I calculate the correct Ballast Resistor though?

Tim