The front axles swap, but you need the steering box and arm as noted in the other post. Also, the B and C grille shells are different (the C works on a B but not the other way around). On some the gas tank pedestal and strap are different too but will swap as a unit.
We put a B axle and steering on my friend's C in about an hour. I'm going to make a narrow front B with my spare parts collection.