I used to run the 160 thermistat in my BB Dodge's it always ran about 180.
The other thing I used to do when I had thin cylinder walls and it ran a little hot
was to run water flow restrictors, Summit, Mr.Gasget, Moroso all make them.
You get about 3 in a package which are differant sizes for differant temps.
They usally cost about 8 bucks for a pack with a gasget.
Kurt