Thermostat change

My 1993 Thunderbird Lx (5.0l v8) recently
started heating up more than usual after I
filled up my radiator with fluid one day.
Now yes, I live in Texas, and heat has
dramatically increased so I understand it
would be getting hot. But! I know that my
temperature readings shouldn't be
fluctuating as high as they are. Im usually
in a middle range, but it's been reaching the
top of the gauge. The only way for me to
bring the temperature down is to put my
foot to the floor and allow it to heat up more
before the thermostat opens up again. At
least that is what im guessing is what is
wrong with it. At idle (hitting aeound
900rpm) it was reaching top guage. So I
bought a new Thermostat and it was rated
at 180° F. Should I keep the one I bought
and use it? Or go for a lower rated
thermostat. It was a Racing thermostat (no
I didn't buy because it said racing. I was
just expecting a 180° F thermostat was a
great one to replace it with.

Thank you in advance for your answers.