A/C to non A/C change

I have a 72 dart that I am going to change from a/c to non a/c and need some advice and or information. In my feeble little mind I am thinking that all I need to do is graft in the mount for the non a/c box and blower motor (see picture) and plug all the extra holes for the a/c tubes and drain hose. If I am wrong in my thinking let me know and if I am right my other concern is the location of the bolt holes for the blower motor. Will I need to put the heater box in to locate the bolt holes correctly or will it not matter. Any help and information will be greatly appreciated.

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