Dave;
Welcome to this Forum!
A small amount of "wandering Timing" is possible even with a electronic ignition (give magnitude!) and "Wear" can also be interpreted in multiple ways (how did you "test"?)...dynamically, Timing should return fairly consistently after blipping throttle...if it does not, Timing Gear Hub separation can be suspected.
Telltale sounds are often emitted by a loosening, but not yet completely separated Timing Gear. See Link!
Statically, if you remove Dist Cap to allow monitoring Rotor position, and turn Crankshaft back and forth at Crankbolt, Rotor should move back and forth also, with less than 10 Deg or so of lost motion of Crankshaft...more then that, Timing Gear Hub separation can be suspected.
I've collected much about TG here, including replacement notes and link to Derek's video, where you can hear the classic knocking noises typical of a TG on its way out (but maybe still good enough to get one home!):
https://www.sw-em.com/Timing%20Gear%20Notes.htm ...and to anwer your question: Yes, TG can be replaced with engine in the vehicle.
Good Hunting from Connecticut!