The K19 does look like it would be a date code, but the translation to '49 or '59 doesn't fit the serial number in this case. The LAQ serial number prefix deciphers as a 1953 powerglide-equipped 235, used in the 2100 and 2400 series cars (as per my 1953 resto pack). That would make the engine one of the first full-pressure oilers, equipped with hydraulic lifters and insert connecting rod bearings (non-babbit).
Finding the block casting number would help verify. See
this thread for help locating this number.