You don't necessarily want the track width to be matched (unless you are trying for a look). The difference in the Wheel Mount Surface (WMS) values is due to the load center relative to the center of the spindle bearing (in general you want the load centered over the bearing, not cantilevered).
For matched Dual Rear Wheels (DRW), the load center is about at the mating surface between the two wheels (which is why the center bearing spindle sticks out so far on the rear axle). For the single DRW spaced front wheel (same wheel offset so that it can be rotated with the rear tires/wheels), the load center is approximately at the center of the front tire (which is why the front spindle is buried in the wheel).
Now in the specific case of the dually rear-end, the thickness of the rim's mounting surface can actually shift the load-center outward from the center of the bearing. You can counter this by using an un-matched set of rear wheels where the offset for the inner wheel is more than the outer wheel - this would shift the load center back to the center of the bearing, but would make it nearly impossible to rotate tires anymore (you'd have to dismount them every time). The other way is to get a Single Rear Wheel (SRW) front and rear axle set, and spacer the **** out of them - this would let you run a matched set of rims all around, and only require that you calibrate the spacer thickness to obtain the correct load-center one time at installation.
The reason for the custom wheels I'm having built is that I don't want to run any non-stock type drive-train parts (i.e. spacers). I have some on my Toyota truck, and though I sized them correctly to center the wheel load center with the center of the spindle bearings, most tire shops I've been to in the last few years won't touch the tires if there are spacers (some kind of liability thing due to too many bad spacer designs/installations).
To figure out the studs, you don't need a part number per say, you need a tape measure. Measure the thickness of your wheel, the thickness of your nut and take the threads-per-inch and divide 2 by that number. Then add all three: wheel mounting face thickness + nut thickness + (2/stud-threads-per-inch). That will give you how long the threaded portion of the stud needs to be. Then measure the thickness of the spindle face (where the stud goes through the spindle), and if included the thickness of the disc-rotor, or drum mounting face. Add those together: spindle face + brake face. That gives you how long the "knurl" is. Then add the knurl plus the thread to get the total length of the stud.
So you'd ask for a "{diameter} x {total stud length} with a {knurl length} stud".
[EDIT:] If you can't find an exact match for this length, get the next LONGER size stud (getting a shorter one would put you right back where you started) [/EDIT]
Since wheels and nuts come in all kinds of thicknesses, and we can't tell what if any changes you've made to the brakes, it's difficult to just quote an accurate part number.
). If your studs are too short to even make it through the nut with thicker mounting flanges on your wheels, you are running the risk of stripping the threads and losing your wheel(s) in traffic.