Before you go off on tooling up for thread whirling or thread rolling, tell us more about the task at hand. The requirements of the job are paramount in the world of sliding headstock machines, as in how many do you have to make, what is the cycle time goal, what machines are available, will the job repeat, and so on.
I find that many times when people go looking for a different way, they've overlooked examining just how inefficient the current process may be. For example, if there is one major, almost ubiquitous deficiency I find in single-point threading it's in selecting the right tooling (often just the right insert) and the number of passes.
I'd guess that perhaps 1 in 20 CNC Swiss-style machine programmers has ever looked up the recommended number of passes for any given thread pitch, selected the best insert for the job, optimized the cutting parameters, pre-turned the correct diameter, and more.
The 1144 stressproof materials is BUTTER to cut, especially in oil. With the right full-form cresting insert, a 1/2-13UNC thread should be done in as few as 5 or 6 passes in that material. With newer machines, the right insert (with today's grades and coatings), you should be able to reliably thread at speeds of over 2000rpm and in some machines, over twice that. Use the tools, they last longer!
Another option I don't see mentioned is Geometric die heads. Those can cut the thread in one pass and be the second-fastest way of making threads. I would think that only rolling in a flat die machine as a secondary operation could be faster.
How many of these threads need to be made, over what period of time? How many spindles are now making them? Has a multispindle machine been considered?
I've done some thread whirling, thread milling and thread rolling (that in both on-machine roll die heads and on flat die 2nd ops.) I find that Geometrics are the quickest. Single point threading (done right) is good for reasonable cycle times in the lower-quantity parts or in the no second op possible situation.
Give more info info about the thread requirements and we can collectively help find the most cost-effective solution.