If i understand you correctly you're saying the fork is too narrow to fit the hub.While the standard for front hubs is 100mm,some old hubs/forks are 95mm.Some solutions to your problem are:
If there's a washer between the cone and locknut,remove it.
Coldset(bend )the forks a bit.
When installing the wheel,set one side in first the pull the other forkleg out a bit to clear the locknut.
I'm sure there's gonna be some folks predicting catastrophic failure and death when messing with the fork,but steel is flexible enough to handle a couple mm.I've bent, filed,clamped down and spread plenty of stays and forklegs and never had a problem whatsoever.