67 318 running temps in the summer

Poly in 67? Interesting. Here in Oz, we got all the US leftovers. The Val coupe sold here in 69-70 was a 68 US Dart. The last Poly here was in 1966.
Here, the way Chrysler was most of the time, the engines went one more year in trucks. So, it's not surprising to see a 67 D100 with a poly for example. I know of two original 67 poly trucks in this area.