groundfungus:
AccelStepper: AccelStepper Class Reference runSpeedToPosition might be what you want.
...I thought so too and this was the first thing I tried, but I couldn't get it to work.
Grumpy_Mike:
There must be something I'm overlooking
It might be that your motor is not capable of running at the speed you want without using acceleration. Try a lower speed.
The motor works at this speed... I tested it earlier with the Constant Speed example code for the AccelStepper