I was lucky enough to find a beautiful pair of '76 Cornwall 1s -- walnut finish with very few scratches/dings given the age. The insides are absolutely pristine -- look like they've never been opened before. Drives are alnico K-77 (round), K-55-V, and K33-E with a B crossover. Caps are the oil can type.
In reading about the B vs B-2, it seems the reason for the change to the B-2 was associated with the change from the K-77 to the K-77-M tweeter.
@Deang -- I've seen comments where you prefer the B-2 crossover and recommend going to that whenever possible. Is the B-2 appropriate with the alnico K-77 tweeter?