Yes, below 150 degrees will get you exactly no heat.
Changing your thermostat and using one made for the vehicle at the correct temperature is essential. However, don't forget to purge the air out of your cooling system, if you have not done so already. This will keep you from getting heat.
Run the car to operating temperature. CAREFULLY and with protective clothing/gloves - release the coolant reservoir cap. Air will come out, and some coolant will bubble over too. Allow the coolant level to drop again, fill back up with coolant to the full line. Repeat.