Was the V8 in these cars the corporate 305 (Chevy) engine?

 

Yes 5.0 Chevrolet.

 

I have a bell housing with Olds bolt pattern that came out of a Starfire. Cable pull arm. What did this come from?

 

Possibly a Buick 3.8L V6 mated to a 5 speed manual. That was a popular set-up in those as were the four cylinders. Changing spark plugs in the V8 version was in a class by itself 😎. I had a 76 Starfire GT V6 5 speed, a fun and economical car.

 

Not "possibly", definitely. The 231 was the most popular motor in the H-07 cars. Take a close look at that bellhousing - many of them only have a starter notch on the passenger side for the Buford motor and thus won't work on an Olds or Pontiac.