There's no such thing as a "67mm bottom bracket". The shell might be 67mm wide if it started at 68mm and then was machined a little over-enthusiastically, but a good mechanic would put a 1mm spacer in there to clean up the installation.

There's a lot of "ifs" in doing your suggested swap: cup thickness, spindle track width, spindle diameter, cup hole diameter, etc. It might work, it might not. It might work initially then fail quickly due to a poor bearing alignment. Only a good mechanic who knows the ins & outs of cup & cone bottom brackets can make the determination.