When the new motors started being used by MakerFarm, little data was found for them. The manufacturer doesn't do a good job publishing data for every one of their motors.

Any of a number of NEMA17 stepper motors would work fine. I replaced just the extruder motor with a Kysan 1124090 I got from eBay. Kysan appears to be one of the premier brands for stepper motors, a number of people use the 1124090 on repraps, and it met the specs called out in the reprap wiki. When I want to invest more in my April 2014 era printer, I'll order more motors and swap out the rest.

Here, the OP is in troubleshooting mode. Colin continued to empahsize that the motors running hot were not an issue, but some of us haven't been convinced. Most of us have gobs of fans laying around from computers and what not. Experimenting with more airflow on a motor is something that can often be implemented in a few minutes. If testing concludes that the motor temperature is related to the problem, then the decision can be made on formal implementation of the cooling fan as a permanent bandaid or motor replacement.