How do you find the engine size on a 1965 Chevy van 6-cylinder 3 on the tree?

There should be a sticker by the radiator to verify the engine size but barring that, I'm pretty sure the only 6 cylinder engines put in 1965 vans was a 230 cu. in. inline six. The only other 6 cylinder available was a 292 but those were special order for pickups. I doubt they put one in a van.