Any question answered...

What cranks? Single sprocket or dérailleur, and if dérailleur how many chain rings, which FD, what's your seat tube diameter? All of these could influence whether a slightly longer BB spindle will work.

And while we're at it, as you sure the clicking is actually coming from the BB? Most noises sound like they're coming from the BB, most of them aren't.

Wow, you've given me some stuff to think on, nope its a bog standard no name crank, 3 piece forged 6061 170mm single sproket, seat post is 27.2 mm diameter, when you talk about FD, I am at a loss, what does that stand for ?, I`m a complete novice, mdcc