I didn't catch your stud issue earlier. I though the only issue was a worn out drum.
Me personally, I wouldn't have 1 right hand thread stud in the same hub with 4 left handed. I would just run that wheel with only 4 of 5 studs. If I had 2 or more left hand stud issues in a hub, and had to change all 5 on the left front to right hand threads, I would have to change the left rear to right hand threads also.
This issue/headache you have is not new. Once upon a time Dorman offered these 7/16 studs with slightly oversized splines so garages could repair in one manner or the other. The right handed with oversized splines are probably still available. Demand for the left hand studs went away because most garages advised their customer, "Let us go ahead and change all left handed to right handed. It will cost you a bit more but this left hand thread on left side issue is over."
For many models they had to remove the rear wheel cylinders to access a hole to poke the new studs in through. Draw the new stud in with heavy washer and nut. Done
To have to tell the first person at the tire store that I have left hand threads on left side of car, and expect him/her to tell the next person who actually does the work is enough complication. Imagine... "This and this is right handed. That and that is left handed except those studs and nuts I have painted caution yellow which are also right handed". If you had worked at a tire store during the 70s or 80s, you probably would have heard something like that from a customer.
