I will say this. Fully threaded pushrods are probably not a good idea. The threads seem to weaken the pushrods,, and being subjected to tons and tons of flexes they tend to want to break. Try it and see, get a 12" 4 40 pushrod all thread and a unthreaded 4 40 rod and bend them back and forth, I will almost guarantee you that the threaded rod will break on the 1st or second bend.
As mentioned I would either go with a rod threaded on 1 end and a Z bend on the other, or a soldered clevis on the unthreaded end. All new model builders should have a pair of Z bend pliers IMO.
All I use now is carbon fiber pushrods. You can cut them to the exact length, they weigh virtually nothing. And you can setup threaded clevis's on both ends once they are cut to length. I like carbon fiber because it is SUPER light and there is no flex whatsoever, plus it is very clean looking[8D].