Thanks for posting this information.

You catalog picture of the 54j action clearly shows the two holes for a receiver sight. The text states that the receiver is tapped on the side "for Lyman and other American receiver sights".

Every rifle that I have seen has these holes barely visible above the stock wood. The stock would have to be cut for a receiver sight to be installed. My 54j was altered, a receiver sight and a front sight installed, post factory work I'm sure. The is fine for me as I prefer a receiver sight for much of my shooting.