On those forks, steer tube is total length so it's 220mm from lower tree to the top. 60mm of thread means the threads start at 160mm from the lower tree.
Top tree thickness is given to make sure the steer tube is long enough to go from the lower tree, thru your frames head tube (with headset cups,) top tree, and still have enough thread for the threaded race and top nut.
Also, Puch uses a f'd up french size thread. 26x1mm. You'll need the Puch top threaded race and the top nut, but you can probably use your original cones and bearings, as long as the races fit.
Make sense now?