itd be really close
1/2" is 12.7mm
minor diameter(think of it as the diameter for the peaks of the threading) thread for 14-1 is listed at 12.773mm.
for a 1/2-28 minor dia is 12.4206
so yes, should be possible. If they can get the tap to rethread with the little bit of threading left behind.
Option B
have them cut barrel down to 14.5 and add 2 longer break. easier math that way.