Formula is one K of resistance per motor Amp. 2.8A motor = 2.8K resistor.
Formula for most efficient PSU Voltage for motor is 32 times the square root of incuctance in mH.
G540 can only accept <= 50V and 3.5A. Motor Voltage much over 50V results in less available torque at speed.
Any motor Amps over 3.5 will result in reduced available torque. EG, 282 oz 4.2A motor becomes a 235 oz motor.
There are as yet no perfectly matched motors for G540. The motors that I recommended for you are the best available that I have found.
CR.