This one is on you then. I ALWAYS go off of the wattage that the motor manufacturer states. rpm and prop size doesn't tell me what the motor is rated at and thus I have no idea what the safe draw is. OP, take it as you will but I would be looking at the wattage of the MOTOR to determine what ESC to go with.
Tony,
The wattage of the motor is only it's maximum rating when operated with it's largest prop and it's highest voltage battery. The actual watts that the motor will pull is 100% dependant on the battery and the prop that you connect (plus the motor Kv). Taking an extreme example, you can take a huge motor that's rated at 5000W but if you run it with a tiny prop it will only pull a few Watts.
If you look at the published test specs for any motor you will see this relationship between battery and prop size which governs how much power the motor uses. For example here is the data for a Scorpion SII-2212 1850Kv which is rated for 22A/326W max.. but you will see from the table that most battery/prop combinations listed dont produce anything close to that:
https://www.scorpionsystem.com/files/i2,226_data_chart.pdf
Having said that, it's not a bad idea to always pick an ESC that at least matches the motor max current rating (if this is published). The thing you must bear in mind is that the motor WILL draw more than it's max rating if you put on a prop that's too big or a battery with higher voltage. Brushless motors are dumb, they dont know their limits, so it's important that the entire system is designed as a whole, including prop and battery.