From the info you posted, it might be a 1968 350 2bbl. rated at 265HP with small valve heads. If it's from a Firebird, code should be WC and should be mated to a 3 speed manual, or a YJ with a 2 speed auto. Same engine was also used in A body as WD or YN.
Heads should be okay, cam, intake and carb could be upgraded for more power.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
