NB Control arms into NA

[toddl1]

My understanding is the upper ball joint on the NA is built into the upper control arm and is not a replaceable part (correct me if I'm wrong). Anyway I've decided that I'm just going to replace the whole arm as they are only $40 from my local Jap importer, but they only have NB ones in stock, I understand that the NB ones are the same as the NA ones but the stud on the ball joint is longer? Am I able to just shorten the stud a little bit then fit it?