School Me On Distributor Performance

Actually so far as OEM advance, "you lucked out" way better'n most of us. That is an early dist and has a fairly short advance. The 8.5 stamped visible in the one photo means you (should) have 8.5 degrees advance in the distributor, which is 17 crank degrees (2x 8.5). What you SHOULD have, then, is (with 10 initial) only about 27 full advance

You are not including vacuum in your readings are you? It should be disconnected for this