Block markings
The 427 referred to was the Z-11 427. Still the 409 style block. Was stroked to get 427". From 3.5 to 3.65. The 814 block would not be a mystery motor block. The deck stampings on the block at the right front would tell what it was. QB was a dual 4bbl engine, QA was 1 4 bbl 400 HP. The 427 Z-11 block was stamped QM. There were others, but these give you an idea how they marked them.
Fred