If you are unable to get a spec on your wheel studs, tap out one of your existing studs to determine exactly what you have.
The most important feature will be the diameter of the fine press fit spline under the head of the stud (also called the "diameter knurl"). Measure the diameter and count the number of splines. Keep in mind that you are measuring a used stud, so the spline area may have been scrunched a bit during assembly and disassembly.
Note the shape of the head. Measure the length of the press fit (diameter knurl") area. Then measure the diameter and thread count of the stud itself.
With this data, you should be able to order a longer wheel stud. It is not absolutely necessary that the spline count in the press fit area be exact. But get the closest you can find.
Using this method, I replaced the studs on my MGA with 3" long Moroso studs and lug nuts in order to run minilite type wheels. The lug nuts are about 1" deep, so they work nicely with the minilites. The studs are quite long, but can be cut down to size quite easily with an angle grinder or cut off wheel.
I was unable to match the spline count on the press fit ("diameter knurl") area, and the length of the diameter knurl wasn't exact. I used the closest replacement that I could find and so long as the diameter is the same, you shouldn't have any issues.
Just to give you an example, I used Moroso wheel stud kit 46450 on the MGA. Look at the specs. That is the information you need to get from your existing wheel stud.
https://www.summitracing.com/parts/mor-46450