You are correct, not stock
you would have loved my car back in the late 70s, it was a two door Olds Delta 88, had the 455 with the turbo 400 trans. I redid the engine, bored 60 over, over sized valves, 400 lift 350 duration cam, shaved heads, double dome pistons, polished and ported, two holly 1250s on top, electric fuel pump, mallory hot box duel point ignition, had a 1500 stall converter in the trans along with a valve body change over.
That, was a running car once you got traction.
oh, and it was primer gray,, the ultimate sleeper till you heard the cam