Greetings and welcome to Just Answer. My name is Mark.
To answer your question directly, I have posted some pictures below showing you the T-stat location. If and when you go to change the T-stat on this, it will be a "stinker" to bleed the air out. They just don't want to "burp" all the air out like most engines
I do numerous headgaskets on these as it seems to be a common failure. Also, the water manifold cross-over gaskets tend to seep. Take a good "look-see" underneath the alternator in the back of the engine. Make sure you haven't any coolant running down the back-side.
Then once you're all set, pour in the coolant as you normally would. Allow it to settle a little bit, then remove the upper heater hose over by the master cylinder. Pour coolant directly into the heater hose a little bit at a time. You'll need patience here as this can be tedious. The hose will fill up and then settle slowly. Continue to pour and let settle until coolant rises and comes out where you put the radiator
cap. Hold your thumb over the hose and quickly put the hose back on the pipe.
You'll know you had success if when the car is idling, you have heat. If the engine is idling and you have no heat, BUT, you have heat when you rev up the engine, you still have an air block. You'll need to let the engine cool down and repeat filling as I outlined earlier.
Let me know if I can answer any questions.
Thanks and good luck............