Will F, M, J-body clutch pedals work in an a-body?

Nah, I didn't. Though the thought did cross my mind pretty seriously, as I have a neighbor who has a 78 Magnum he has been trying to sell me for years and I secretly have always wanted one with a 4spd and 440...;)
A 78 Mag is a B body though. I don't know if the F pedals would work