When does it heat up? Driving, cruising, traffic?
In my opinion, I don't think drilling is going to help you. Drilling the t-stat is to bypass coolant before the t-sat opens or to help burp the air pockets out. I drilled mine on my BBC because I have no prevision for the factory style bypass. Once the t-stat opens it doesn't matter if it is drilled or not. You could try a high flow stat.
The manifold is about 10* cooler than the head.
Also, what type of shroud do you have?
I would just put the 180 in without drilling and lower the temp at which your fan(s) come on.
Last edited by NOlowrider; 01-02-2011 at 06:26 AM.