You have more than chain stretch involved with that timing issue. Somewhere the gear has been put on wrong. Move the gear forward a tooth. That gap is more than a tooth wide. Back when it was practical to dial indicate and compensate timing I used to see right side gears as much as 14degrees retarded after 250k miles. Fourteen degrees is a little over an 1/8 inch. A one tooth movement will change the timing 18 degrees.

Don't even think about offset woodruf keys unless you plan to do a real dial indicated measurement of timing.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician