Fixed.Syntace across the range will be your best dearest option
The flatforce are short stack but also drop the bar height, which may not be what the OP is trying to achieve.Syntace across the range will be your best bet.
Steerer needs to clear the upper clamp bolt.
32mm... Which is also about the same as the Ragley stem Moorey mentioned above.Funn's Funduro stems come in 45mm and 60mm options from memory and the stack height is really low, I can measure one later tonight if you're interested.
I do like the race stems.spank spike stem comes in at 35mm, built like a tank too