I'm using a pitbul rear stand and it's fully adjustable and works great.
How are you attaching the spools to the swingarm? Most people use the $30 Chinese endcaps or the eqivalent Area 22 $60 ones. The only difference is that the Area 22 is in stock in the US and ships immediately, while the other ships from China and takes 3 weeks.
With those end caps I use a harbor freight rear wheel stand. The z125 is small and light, no real need for a big dollar Pit bull stand. Thought if you have the money it never hurts.
The thing I like about the harbor freight stands is how light they are. I use them equally well on my baby Z as well as my big Z. Though on the big bike, I retrofitted higher quality wheels on them.
I have an adjustable PitBull that works, but I've had it for years. Agreed in this case that the cheaper ones will suffice being that the bike is so small and light. It has to be a width-adjustable one, however. The ones that are a standard width are too wide, I have a couple of those, too, so I know they're too wide.
Note, I have the Area 22 spools on my Z