Dimensions of JST GH 1.25mm pitch 3-pin

I’ve read here that the official dimensions of the JST plugs may be off or not precisely correct. I am also unsure if I understand what is described in this paper, correctly.

My original problem:
I have a JST plug with 3-pins of unkown size. I want to find out the size of this plug and buy a proper replacement. The pitch is between 1.0mm and 1.5mm, that I am sure. However, it is really hard to measure such tiny lengths, so I want to be sure what size to buy, before I buy JST plugs again, which are the wrong size.

Does anyone have spare ones at home that they can measure as precisely as possible?
I pretty much only need the size of the plug itself, not the spacing size. That equals to the size B in the Housing section of the paper I linked above. That is the length I need, so I can compare if, for example. the 1.25mm pitch JST GH plug is the correct one to order.