In some high end Saturn automobiles, there is a 75 deg. V6, derived from a European GM design, I believe.
The ideal bank angle for a V6 is 60 deg., and for a V8 its 90 Deg., 75 being right in the middle.
Does saturn plan to expand the tooling for this V6 to become a V8?
Well, your confusion stems from the fact that you have the numbers wrong. The Opel-derived GM V6 used in the Saturn L series and the Cadillac CTS is a 54 degree engine, not 75.
The angle is narrower than the “ideal” 60 degree angle for packaging reasons (same as the VW VR6 engine). The narrower engine allows for shorter hoods (when mounted transversely), different suspension designs (when mounted longitudinally) and so on.
I don’t believe any GM V8 engine plans in the works are based off the V6 you mention. Current V8 plans are new designs or revamped old configs.