i'm sure that's what they are called, but i know you have lots of different ends on the ends of them

here's the dilemma:

this is what i've got

it's for an anti roll bar drop link
how much of the threaded section can i leave to be the "adjustable" bit before it's not enough?
half?
more?
less?

curently it's got half the threads in, but i need to have virtually all of it out to give it the correct length it should be, but there is no way i'm going to do that, but is half the threads in, roughly and inch, enough to make it safe?