I recently bought alloys for my 68. All 4 wheels are LBP with 1/2"-20 studs.Test fitting the bare wheel on the rear I found the thread engagement of the nuts to only be 7 threads which calculates to 0.35. Approx 11/32") at 20 threads/inch. They are stock Chrysler studs measuring 1.72 overall including the head inside the axle flange.
As a minimum I want to see at least 1/2" engagement, the diameter of the stud which is a basic engineering principle. I haven't checked the front yet which are 73-76 discs.
I remember looking for longer studs in the past but it's been awhile. For me an overall length of 2" would be ideal. I was thinking of contacting Moser to see if they offer anything. As a last resort I was thinking shortened 3" drag style studs. My correct nuts for the wheels are closed end so I can't run open lug nuts with these wheels.
I'll try to see what I can find and get back here.