This era of numbers on the LS open boats can usually be found on the interior, way up under the gunnel.
Typically upside down, in the stern or bow.
That being said, they're not always easy to decode.
They certainly help with registration, though, as they are unique numbers.
Also, in my opinion, you're definitely on the right track with it being a Corvette.
I have most of the era's factory catalogs and it appears the Corvette ran from 1955 to 1958.
Structurally, it looks like the '55 had an actual transom knee and the '56-58 used the horizontal Lone Star Power Bar for transom rigidity.