The bracket is different from 67/68 to 69. I'm 99% sure you can just change the pedals without changing the bracket. I just did a brake swap on a 68, and I removed the manual pedals for an auto pedal. Just remove the clip & slide pin out. The manual pedals go in from the left side, so you may need to make a little room on that side of the bracket depending on how things are routed under your dash.
The brackets are different, as are the pedals. Actually, only the brake pedal is different. The brake pedal stop on the bracket is in a different spot.All will interchange, the difference would be where the brake pedal returns. If mixed, the brake pedal would not return "even" with the clutch pedal.
I just went through this on my 67, and ended up with 3 sets of pedals and 2 brackets to discover all this. What's crazy is I had mixed pedals and bracket on the car for nearly 30 years!