Joe, First off I would 2nd Phil's (Phak1) comment about the casting date of the block most likely being for the 1954 model year. I think the '54 models were most likely already being produced by that point. A little reading through the
1929-54 Chevy Master parts book, looking at the individual engine component part numbers show the majority of the engine parts fall under the same part numbers for 1953-54 passenger engines with the powerglide transmissions. It's possible the only definitive answer is to inspect/measure the parts you find that could be different in the parts book to figure out which one you have and need. That method is a pain in the backside as you can't simply pre-order stuff (unless what you need you can confirm in the parts book is the same for both year engines).
Another possible clue would be to locate and post your engine head casting number (outside the valve cover centered on drivers side of head) and casting date codes (under the valve cover and just inside of the casting code location). That info could help pin down more details on what you have. That's a 'big if" though if the head has been changed out???
