New VR for Pertronix III?

I just got the Pertronix Ingnitor III billet plug n play distrbutor and the FlameThrower III coil to replace the stock points/dizzy in my 440 - '69 Coronet. Do I need to upgrade the VR to a EI version? I've read posts that the post-69 VR is needed but when I talked to Pertronix tech, they said as long as the ballast resistor is removed and 12V gets to the coil it doesn't matter what VR I have. I'm so confused....