1968 A-body 383 block and front left motor mount bracket. $500.00 plus shipping

Just because this came out of an A-body doesn't mean it's a "factory installed style/type" A-body block. Your pics show this. Any 383 will fit in an A-body.
Must be an over the counter 383 block replacement for any style body (no VIN).
Surprised davescuda hasn't elaborated on this???
Not sure why your hung up on this going into an A-body? Just sell it for the first $$$$