I've had a chance to check out a few more drawings at the NARA and stumbled across this drawing from the Passaic class ships (which appear to be the design that immediately followed the Monitor):https://www.flickr.com/photos/149550464@N04/32571476231
It's undated unfortunately, and it documents the "Battery Engine" rather than mentioning the turret, but the style of the text and look of the drawing make me wonder if it might date to the civil war period.
Also, if Wikipedia has it right ( https://en.wikipedia.org/wiki/USS_Passaic_(1862
) ) the civil war ironclad Passaic was in service in one form or another until late 1898. That may indicate that the following drawing also pertains to the same ship, although it's not immediately clear what alterations were made over the years that would be reflected in the drawing:https://www.flickr.com/photos/149550464@N04/32693655015
There may or may not be any useful info in these, but I thought I'd mention them in case