Dont need to stress this is boiling water and you have to proceed with
caution
Cut off the bottom of a plastic soft drink bottle,Then wrap some tape around
the neck ,so that it fits
snugly in the radiator filling hole. Fit it ,
Then fill it with antifreeze-mix and start the engine ,
You should see air bubbles coming out and the fluid decreasing as the
enginewarms up.
Finaly ,when the engine is hot ,and the thermostat has opened (radiator hot)
increase to 2000 rpm ,and whille at this speed take off the bottle and put
on the radiator cap.
(this will press in more coolant)
Dont forget to fill the expansion tank up to the mark,

.

Can you verify that the new stat is the correct heat range?

"When a legislature undertakes to proscribe the exercise of a citizen's
constitutional rights it acts lawlessly and the citizen can take matters into
his own hands and proceed on the basis that such a law is no law at all."
- Justice William O. Douglas