Paul's reference to Alden is probably the best general info available. If you have a specific boat in mind, the best source would be the pre and post conversion drawings. Framing is shown in the Booklet of General Plans as well as detailed hull drawings.
However, frame numbers can vary by 1 or 2 depending upon whether the G-III is a conversion of a TENCH boat completed as same or a TENCH boat that had construction halted at the end of the war, then redesigned and completed (as opposed to converted) as a G-II in the 1947-1949 timeframe. VOLADOR SS-490 is one of the latter.
I'll recover the frame numbers from my qual notebook, but I can tell you this much right now -- during the G-III conversion, VOLADOR's pressure hull was cut on the Control Room side of the Control Room/Forward Battery bulkhead, some 3" or so aft of that bulkhead. Thus, the Forward Battery compartment remained untouched insofar as the additional hull section was concerned.
Once the two sections were moved apart to permit insertion of the ~ 15' additional section, FADM Nimitz came down unannounced after dinner one evening when Hunters Point was quiet in order to see this unusual sight. I had the duty and was awestruck when I realized who our visitor was, as he arrived in one of those long black Chryslers that admirals had, but his flag was sheathed. The old gent spryly hopped out of his sedan before his driver could make it around to open the door for him.
After having a lengthy look from the apron, he went aboard the boat in drydock, crawled around all of the wires and air hoses, and toured from stem-to-stern, asking a zillion questions along the way.
I have no idea how old he was at the time, but he navigated his way thru the maze as if he was 18.
What crew we had remaining during the conversion were housed and fed in the barracks up on the hill, but we had a small ("unapproved") galley set up on the barge. As it turns out, we had "requisitioned" some cherry pie and ice cream from the galley that evening and he instantly spotted the contraband. As he put it, it was necessary for him to inspect the "evidence" - which he did, two heaping helpings worth.
I had never been within 100 yards of an admiral before, so you can imagine what it was like to actually shake hands with a 5-star WW-II hero the first time out.
