You do not need the expensive Dynatron motor to drive the Miller Persuader on 24 V. The 4:1 reduction provided by the Persuader reduces the current draw of the starter motor so that you can use a standard Sullivan starter motor on 24V. You need 24V to get the speed required after the reduction. I use 8 A123 cells.
I have had a standard motor on a Persuader since 1999. I have used it to start a BME 102.