Normally I would say going to a lower temp thermostat is not the best practice especially when you're dropping it so much. You would probably drop you gas mileage and cause your 02 sensor to seldom take effect. Now that it's been said...
Given the fact you probably have the sensor already removed and are going to race the machine, it shouldn't be an issue. If the average temp actually stays at the rated 165 F because of that beautiful rad (It's the rad that lowers the temp, not the thermo), you will be able to run a richer mixture, get potentially more power and advance the timing a bit more. Also helps with running higher compression pistons. Looking forward to those dyno numbers.
, will see, heat most definitely robs horsepower, you can see it when tuning you think know you made change to get more but fing heat, thats what ive seen watching Konrad and cussing, i know by that too, @Gerald Konrad said he lost ponies like on mine when he tuned you up, how’s yours running since? once it gets around 185 it struggles making power, heat is an engine builders enemy
learnin 
