You can get a lot of hints by looking up the units Newton, Newton-meter, Joule, and Watt on wikipedia and looking at the equivalent conversions to other units 
But I messed up that final calculation, which I probably wouldn’t have if I’d written the units. First of all I forgot the seconds. That would make it 0.030kg x 0.024m x 417rad/s / 0.4s = 0.75kgm/s². But that’s the dimensions of a Newton, so to get torque, we must need radius squared (which makes sense, considering that it’s an acceleration). So the correct answer is 0.018Nm, no problem at all! The 5010 360kv motor driven by B-G431B-ESC1 should be plenty strong enough for this project. But the ESC1 is sensitive to overvoltage, so you’ll need to add a braking resistor circuit to burn off the deceleration energy. Here’s a good old thread on the topic https://community.simplefoc.com/t/protect-power-supply-against-bemf/2459/47
It’s true that the V rollers will add some friction, but since rotor inertia is the much smaller component of torque, the pulley size can be reduced to get more power out of the motor.
P.S. Another nice mental trick when dealing with torque is to imagine 1Nm is a 1N force on the end of a 1m long stick. Picture that making one revolution, it sweeps out quite a large circle, 2pi meters. Especially helpful for calculations involving leadscrews, to understand where the huge force comes from when you reduce that 6.28m of circular motion to a few mm of linear motion.