Attempt to get the FATTEST spark plug arc
Not sure where you got the 1 amp per 1000 RPM. There isn’t a battery fired ignition I know of that gains power with RPM.
And I don’t think the old MSD 10 boxes made an amp.
If you want amperage (don’t we all) then you need to get a magneto. Not the Vertex style with the internal coil, but the Mallory with the external coil. You can send those out and get 5 amps easy. 5 actual amps, not the MSD wonky method of measurement.
I personally wouldn’t use a 6 box on anything but a dead stocker.
Wait for the guys to chime in who run 5 second 1/4’s with and analog MSD 6.
The 7 is the MINIMUM box any performance engine should use.
As a very smart dude once said, “you can’t have too big of a fuel pump, push rod or ignition”.
I agree with that 100%.