If that's the original engine to the car, there is about a 99.9% chance it's a 272 and not a 292. I've never seen a '55 pass car with a 292 original engine. There may have been some police cars made that way, but don't know for sure if they made any. If the car still has a VIN plate on it, it more than likely has an "M" for the first digit, which means 272 4 bbl. A 292 would have been a "P".