Actually they are not the same. The pedals themselves are the same but the pedal bracket (that is the box) is different. You can google and see the difference in the pics. I believe they may be interchangeable but definitely different To look at.
Just buy a clutch pedal from Modern Driveline and put it in your auto pedal box...the holes are there already. Then trim the auto pedal down to the manual size with a cut off wheel and put on the proper manual brake pedal rubber. (This is what I have done with my own auto to manual conversion on a 70)