carb questions

[yfz450admirer]

I have a couple questions for you. I just got my 450R carb. Do you know if the 450R throttle cable will match up to the 400EX. Also, will 400Ex main jets work on this carb? I looked at it last night and I couldn't get the jets to match up. There was no main jet in the carb when I got it and the needle jet holder was just floating around. Any ideas on how to fix that? What secures the needle jet holder, what do I do with the locknut on the needle jet holder.
Thanks in advance!!