Shifter threads

Just got my shifter handle and mechanism back from Passon. Stick was rechromed. The chrome shop screwed up the threads so that now they are 'less' than the 3/8" fine thread they should be, but larger than 5/16". They now are "mystery" threads. Now stock knobs will not thread on. I need a suggestion on how to repair the threads without damaging the new chrome. This is a very rare stick- '68 cuda 4-sp with console, so must find a way to repair this one. My only idea is to build up with epoxy and then re-tap back to 3/8" NF. Got any other idea's? Help!