Re: Tire width
The car does have 67 taillights, so I would agree 67.
The guys have already alluded to what it takes to properly fit tires of that size; more rim backspace, and mini tubs (deeper/wider inner wheelhouses). Plus relocated leaf springs (and narrowed fuel tank or a trunk mounted fuel cell) or another type of suspension out back.
The way the body sides of these 1st gens tuck back in toward centerline, it is hard enough to keep paint on (and rubber/road debris off) the lower rear quarter panels with stock or nearly stock width tires. If you looked at the car in the first post from directly behind, about 2/3 of the tire tread is outside the body line at the bottom. Not a good look IMO.
69 'vert project big block/TKO 600 RR
68 'vert driver RS clone -- gone!