The 127 tooth gear is supplied so metric threads can be cut on a lathe with a imperial leadscrew. (127 is the lowest interger. 25.4 X 5 = 127)
When not using a 127 gear, is the 1.0mm pitch correct or just very close?
I suspect the later.
Some gear suppliers have drawings of gears which can be view at their web site. From these details, you may be able to determine the pressure angle, DP etc.