I'm going thru the same issues with my Willys. There are at least 3 stock type front anti roll bars for the Must II. Unfortunately they are designed for the real Must II which is about 3400 pounds and about 60% on the front end. I got one and tried it out. I have the lightest springs available for the coil over Must replacement shock/spring. It should just float on these but they are still too stiff. Not only that the single adjustable shock are valved too stiffly. There is so much compression in the shock that the ride is really rough. It handles quite nicely but the ride leaves a lot to be desired. The anti roll bar I have was so stiff that going over even a small bump with one front tire caused the other side to follow almost exactly. Inother works way too stiff. I'm told all front anti roll bars for the Must II are about the same. My nice shiny new anti roll bar is now standing up in the corner by itself.
If you can make some nice mounts for the Speedway sprint car anti roll bars, they should work nicey. I'm thinking along the the same lines. Speedway may work with you on exchange but don't mark the bars up.
For the rear there are a number of setups available. All run $250-$450. These are short and very stiff bars as they are normally used with narrowed rear end.
You will need to make your mounts to give you the roll center you want.
My case I have a very narrow rear end with the shocks only 18 inches apart. This means the springs are pretty ineffective at countering torque from the drive shaft. One wheel wonder. yeah you can install a Detroit Locker and make it so both tires spin but al it really does is drive the left tire hard and the right tire just more or less goes along for the ride. The car will drive hard to the right (rear goes to the right). I've already proved this. so I'm also working on a very stiff rear anti roll bar.
I too have the calculation somewhere but SolidWorks gives a very close answer and is much faster and easier.
Be aware that small changes in diameter of short bars changes the rate very significantly. It is also possible to overstress these stiff bars and cause them to stay twisted.
Finally it's not really necessary to depend entirely on the splines for adjustment. Design an adjustable link. You can even preload the system with these.