Master Cylinder pushrod questions

Greetings all. A few questions:
1. Will the pushrod from a single pot m/c ('65 Valiant) be used in a dual pot m/c?
2. If so, is it held in the same as a dual m/c? The rubber retaining ring?
3. Anyone know the length from the back of the single m/c to the center of the pedal hole?

Planning on doing the upgrade. Have a drum/drum m/c and pushrod from a '72 Scamp on the shelf. I have read in a few threads about using a m/c from a 67 to 69 car.

Thanks for any input. Bruce