Hey Bill,
the 230 V Version of the Stepcraft MM-1000-DI has a 4,000–25,000 rpm range. In fact I don’t know why the US 120 V version is only specified with 10,000 – 25,000 rpm. I don’t know why you want a 120 V version because in the US usually you have split-phase electricity which means 120 V between one hot and neutral, and 240 V between two hots of different phases. The Stepcraft has a nice digital speed control interface.
Also the Mafell FM 1000 PV-WS (with quick tool changer) and FM 1000 PV ER (with ER collet) are rated 4,000–25,000 rpm. They have an analog speed control port that you could control via a PWM converter by the Onefinity controller. You could control the rotational speed using G-code commands from the g-code program like you would do with a spindle.