This is definitely a 6 cylinder, Vantage, DBS
Chasis No. DBS/5234/R Eng No. 400/3831/SVB
It was a works demonstrator, & special engine built in the experimental department,
One of two cars used in the film... This was registered as GKX8G and was used for all the external shots,
The other car was used for the internal scenes, with cameras being set up and mounted on the side of the vehicle.
The V8 was first used in 1969 so it could be either. The V8 had a new grill and the mirrors where located further back on the later cars. This Looks like a 6 cyl.