Thanks guys. I think it's safe to say that I've managed to tap into a wealth of knowledge in this headset arena! As suggested by most, I'll head down the path of cutting the stem a bit too long, and just use a spacer or 2. Plus of course, it will look a whole lot better than what would otherwise seem a cheap solution with excess thread sticking out the top of a non-capped nut. So, I'm about to embark on the, "measure twice, cut once" method of cutting my stem.

Cheers guys.

Stuart