Got a used 99 Litespeed Ti frame and fork. Current setup is threaded, 43mm rake and 140mm steerer tube. Since I'm replacing the fork I learned there are 2 ways to go.

1. Get the Nashbar 1" carbon fork. The shortest steerer tube listed is 160mm. I think this will be the cheapest and easiest way to do it. Can I cut it to be 140mm?

2. Replace the threaded headset with a threadless setup and install a 1" full carbon fork. More $$$ but will have a more modern and lighter setup. If I go this route what type of headset will I need?

I have built a bike from the frame up so I am confident I can do this. I just need some help in getting the correct parts.