Well, for good power to size and being able to control the speed, brushless is great.
If all you want to do is control the speed (a plain spindle), a full brushless servo drive may be a bit overkill. An R/C airplane shop could probably set you up with a speed control that just makes it spin, or see what the guys selling these motors recommend.
If you want to do live C axis work like rigid tapping, then you do need to get a brushless servo drive and encoder.
You'll want to make sure you have can get enough hp out of those motors for the work you want to do. Torque is basically constant as speed drops, so see if you can get specs or compare it to something you know would work. Also be sure they're ok with being under load continuously.