I am planning on getting a newer frameset (pista concept) and I really want to keep my gold nitto pearl stem. Would I be able to thread the threadless fork? Would it be easier to get a threaded carbon fork instead?
If It is possible to thread the fork:
does it compromise structure?
is it expensive?
Most often, a threaded fork steerer will be thicker than a threadless one. You need the extra metal to compensate for the thread cuts and the force of the quill wedge. So yes, most likely you'll need a new fork. I'm thinking steel steerers here, I don't know what the Concept comes with. If it's an aluminum steerer, there's no debate-new fork time.
Also the threadless tubes I get to build forks are butted, (tapered internally in this case). So the internal diameter is variable, which means the stem might not fit properly, and I don't even know if they are in the right ball park anyway. I bet there is some way one could fabricate aroud these problems if a person really wanted to make a one-off, but in the normal case it would be a lot better to start with the appropriate frame in the first place or accept the threadless stem for what it is.