While driving to/from work and around town today, I no longer heard the signature spark knock sound. I did, however, notice that:
-It still runs just as hot as before, if not more so
-I'm lacking a noticable amount of power. I occasionally notice a very low rumbling idle, and I also occasionally need to give it more gas than I used to to keep it from chugging while driving around at low speed/gears.

The fact that I'm lacking power, in spite of the ignition timing still being further advanced than It should be, seems very odd to me. Shouldn't it be the other way around?

I also tried checking the vacuum advance, but I didn't see anything that resembled the vacuum advance pictured by Haynes on the distributor. Is this particular model supposed to have a vacuum advance?

Here are some pictures of my distributor in case that helps with the vacuum advance:

From the top/front:
IMG_2749.JPG

From the bottom/front:
IMG_2750.JPG

From the top/left:
IMG_2751.JPG