lots of vertical travel probablt means that the top nylon bush has broken up- its what holds the top half of the dizzy shaft onto the bottom half.
top half holds rotor arm, bottom half holds advance weights - if it lifts up too much then it can pop out of line and the timing will go way out
needs the dizzy stripping/checking, and no doubt a rebuild kit would help
can you check no1 tdc at your current dizzy setting and see if it is far out?