A very doable project I'd say.

I would get 2 bolts. One for the 223 and another for the 243, 260. Changing for the other cartridge then gets real simple.
And get three of the smooth nuts. Headspace the barrel and add a set crew to keep the nut in position on the barrel. This gives a nut/barrel combination already headspaced together. Again changing to another cartridge gets real simple. But but still separate components just in case our minds change.