Needs to be a high flow thermostat. I like running a 160. People will argue, but that's what's worked best for me through the years. Whatever you run, the high flow part is very important. Also make sure your pulley ratio is right. The water pump should be turning faster than the crankshaft. In other words, the water pump pulley should be smaller than the crankshaft pulley.
I will make sure to get a high flow thermostat. Also, The pulley for crankshaft and water pump look to be about the same size from the photos I have. I got the pulleys from a 318 I parted out so I assume that they are correct.
