Re: '59 pole spacing narrow compared to most Humbuckers?
Newer Gibson humbucker pairs have wider pole spacing for the bridge, older didn't. Pretty much all other humbuckers have roughly the same, but not same enough to freely interachange covers (annoying).
I haven't tested it, but the change in the magnetic field, from wider spacing between the polepieces, will certainly make a difference in how the whole thing behaves. But that's just the thing, the wider string spacing isolates the strings more, they don't mess with each other's polepieces as much anymore.