I think you'll find the screw in ball joints are available in different sizes. I think this is the smaller one
910 34323 - Speedway Motors, America's Oldest Speed Shop and this is the larger one you'll need
Speedway 1960-66 Chrysler Screw-In Lower Ball Joint - Speedway Motors, America's Oldest Speed Shop
You may need to do some measuring to figure the tapers out, we can help with the math if need be.
I have seen tubular swaybars before. You could check your rates here
Sway Bar Rate Chart I would drill and tap a series of (3/8-24) holes in the end of the arms to make them adjustable and simply tie them to the lower arms by the shock mount with heim jointed radius rods. The old rubber bushed ones come apart 45 yrs later.
