I have the following lying about, I found it online a while back from the University of Colorado Electrical Engineering course ECEN2830. You might find it useful to you.
There are two .asc files in the zip file (1) DC_motor_model.asc and (2) DC_motor_model_test.asc
The motor model includes the back emf and the current changes as the load changes. There is an input that you can use to control the load.. The test file uses a PWL current sink at the load control input (omega) to apply varying loads. The test file applies the voltage step to turn on the motor, and then turns it off, at which point you can see the current draw and the back EMF at the motor's +DC input terminal. The model accurately depicts the current changes due to load changes as well.
There is also a PWM motor speed encoder output.