Look for pics of B Tower's panel. It was in the Hillside Signal Lab when I started, I believe the MTA museum in Brooklyn has it now. Also, look here on Arrt's page:
https://www.arrts-arrchives.com/bethpagejunction.html and you'll see the diagrams for the 1920's era plant, and then the one that came later. In your map you have (unless I read it wrong) G-289 labeled as the home signal to B Interlocking. Back then the home signal wouldn't have been an automatic (letter + mp number, so G-289 would've been automatic signal Mainline approx 28.9 miles). In the earlier machine the westward home signal for B would've been 1 signal, in the later one 16R.
That's one of the westward home signals, the ones you're looking for are (between Central Ave and Bethpage parkway) are the eastward home signals, which in the older machine would've been 16L on #1 track and 14L on #2 track. Later on (late '60's?) they put a siding in west of B for General Motors, and they interlocked that switch and made the eastward home signal on 2 mainline now 8L, and removed 14L. So, it depends on the time period.
