Would it be possible to use the original case around the new switch? Just a thought to be able to have one that at least looks period correct.
I have the new one from JC that I painted to match the steering column, but after John's mega thread on using a 4 wire switch, I restored my original AutoLamp switch and will be using that with a 4-relay block hidden under the dash. The relays should fit well attached to the steering column support.