Yes the five speed vert gears can be put into a 160, put it's not a bolt in proceedure. It requires some machine work in the shift drum/plate area.
I've never done the swap myself but from what I've seen (I have drawings that outline the mods needed) it's a much better bet finding a set of 175 sloper cases and using them. The Vert 175 gear set/shift drum will fit right in 175 sloper cases. So...even if you find a set of empty 175 sloper cases you can use Vert 175 gears, crank, clutch, almost everything....the shift shaft is a tad different but will still work.
The sloper 175 engines are getting hard to find though. They are a better set of cases than the 160 too. More robust in the mounting areas etc.
Yes it's worth it, the five speed is much better. That extra gear is worth several seconds on the average race track.