Well, my first thought would be to check with John Mottishaw to see how they actually remove from the pen, as well as what they're reasonably close to in size (vintage or modern). I don't know the approximate dimensions of a #15 Pilot 14K, but I'd imagine that they're reasonably similar to the old-skool Duofold nibs. Perhaps you could dig up a nice Big Red sans nib and slot it in there? If you ever wanted unique, you'd have it there.
(Oh shut up, all you purists who are gasping right now...he loves the nib! Wait 'til you see what I'm fixin' to do with a Thompson that's on its way...)

Anything work out with Edison?