I got my info from a DT125E parts catalog, though for some strange reason the service data pertaiined to DT100? ...misprint?
I dont have any info on voltage, neither do I have a bike with points, my source coil generates around 130v to a CDI unit and measures hundreds of ohms...lots more turns than yours
of couse you see a varying resistance as the points open and close...think about it! closed you are measuring a dead short through the points...open you are measuring coil resistance
I dont recall you saying that you tested the HT coil and that is within specification ?