340 running hot

Yes. This lower thermostat myth needs to go away. Look at it this way....

Let's say your car is ringing at 220 with a 180 stat. The 180 stat (if functioning correctly) is open at 220.

Now, if you put in a 160 stat in an attempt to solve the issue of the car running at 220, what happens?

Well, at 220, a 160 stat (if functioning correctly) will be open.

So. An engine running at 220 with an open 180 stat or an open 160 stat are the same.

You have done nothing but spend time and money to achieve the same end result.