I have had 2 pedal sets in my car, one I pulled from a 318 duster, the other came from a '67 3 on the tree car slant car.
Both pedals have the exact motion/ratio, and both came back up all the way...
I do not have a '340 pedal set', if it's really different...why they would bother with different pedals I dunno..
You're gonna have to explain that one to me, if you don't mind?