Converting to a Non-A/C Heater Box: Questions That need Answers

In the process of Rebuilding a non-A/C heater box for my 65 Barracuda Build.
Issue I'm having is the car was organically an A/C car and the fire walls are different between A/C and Non-A/C.
I tried searching for these answers and got Super Frustrated , as a result here is my post Sorry...

1. Has anybody here dealt with this personally?
2. What was your fix for the fan motor mount / hole?
3. Does anyone sell an adapter plate or easy DIY for swapping heater boxes?
4. If not Has anyone done a write-up or post thread about doing this swap?

Thanks in advance!
Open to any and all suggestion and options, info, comments, name calling, what ever...
j