Correct internal or external coil for pertronix points eliminater

Mike,
Well aware of the collapsing field in the pri side generating about 200-250v, & it is this that multiplies with the turns ratio.

It seems that coil makers have gradually woken up to the fact that it is the heat [ the heating affect of DC current ] that ignites the A/F mixture, not the voltage; the voltage is merely the enabler of current flow. Many E core have lower TRs than the 'performance' coils of yester year that were often over 100:1. The 1" spark looks great on the gadget at the speed shop, & 60,000v is waaaay more impressive than 0.1 amp, so guess which one gets the sale, lol.
These are the TRs of just a few ind ign coils that I have specs on: Crane PS91 54:1. Crane LX-9