I found an article that talked about the V8 Beretta/Feretta, and it says it used a 3.5L engine. Was this a one-off engine or based on something else? Though they do talk that there might have been a Suzuki/Japanese connection.
I'm also thinking - Could this engine have been an outgrowth of the cancelled GM80 program?
This is an interesting quote in the article "GM management was seriously considering replacing the F-body Camaro with variations of the L-body Beretta"
Does this imply that when the GM80 program was cancelled that the Beretta was actually a variation of what the 3rd-gen Camaro would have looked like?