As Cletis mentioned, the LEA on the title would be the prefix of an engine serial number. However, LEA is a prefix for a '53 6000 series 235 truck engine, not a '54 235 or 261. The engine serial number format changed in '54, and used suffixes instead of prefixes.

Check this picture for a possible location of the casting number.

Curt
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1953 Chevy 6400, 1957 Chevy 2dr Sedan
--"Mediocrity is easy, the good things take time"