can an AC 110V motor controller be used with a bridge rectifier work as a DC motor controller
would an AC power supply, with heat sink and fan, connected to a bridge rectifier work? The dc motor is 48VDC 300W

The motor is rated for 48VDC. You should not supply it with a power source that is above 48V. AC is generally given in RMS voltage which is only about 0.7 of peak voltage. Thus, 35VAC, when rectified, will give you something in the ballpark of 48VDC. If your AC supply is less than 35VAC you can rectify it and apply the output to your motor. If it is more than 35VAC, there is a good chance of damaging your motor and possibly starting a fire.