Heater box replacement

I am pulling my A/C heater box out of my 1970 Dodge Dart and want to replace it with a stock Heat only box. Does anyone know if there are any conversion problem at the firewall?
I have heard that it requires a different templet and blower motor location.

The following pic will help you see what you are up against. The hole for the ac fan motor is much larger than the heat only boxes. You would have to make an adapter to cover the hole
The black outline is the size of the AC firewall

So this is from the engine compartment side , other than the motor port and plugging of the condenser coil lines all other points are the same ?, heater coil included?

The wiring harness is different also.

'We ordered the wrong harness for our 71 valiant. It is an A/C car and we got a heater only harness...

However, if you study the wiring diagrams, we were able to use the old A/C wiring with the new harness, by just transferring the main power feed wire from the heater only terminal into the old harness power feed connector....

On the a/c car, the main power feed wire is black and goes to the a/c control, then the a/c control feeds the power into the blower switch...

For the heater only car, the main feed wire is black and goes in the center terminal of the blower switch.

If you find a heater only wiring, then just pop the black main power feed from the old a/c harness out of the connector and then install it to the center terminal for the blower on the heater only wiring and you'll be good....