My 71 was an auto and had the correct support for clutch pedals ... I had the clutch pedals installed in less than 10 minutes. More than likely you will need to remove the steering column to swap the support. I have the same issue with my 74 car. I plan on swapping to a stick shift and need to replace the support on my car as well. I have no idea why Ford went to a different support in the later year cars ... pain in the neck ...
I swapped my support when I went manual and again when I went back to auto. I didn't have to pull the column just dropped it down. If I remember correctly. 4 bolts at the firewall, 2 at the dash, 2 more through the support into the column. Disconnect the MC push rod. And disconnect the brake light switch. If I would have tried to swap the pedals around I could have saved myself some time. That was a long time ago though.
I will be driving it all this summer with the auto, just trying to get some things together for the winter months up here