273 Intake Manifold Question!

I had a 68 Sattellite 2 door on the lift years ago. This was back in 07 I think. the car was original and the guy was like "Its a 318 I think" I looked at the numbers on the block it was a 273. He was surprised by that. The owner didn't know he had a 273 in that B body. It was a nice original condition car.