The stock value for the low speeds fans to switch on is 212f and will switch off at 205f. No need for adjusting the fan in the tune for a thermostat change, but you might want to do that with a stock thermostat anyway to keep the low speed fans on all the time during the warmer months.
The spark correction for coolant is zero at 180f and 200f but will interpolate below or above these temp numbers from the 150f and 220f points. There is a chance that timing will be affected slightly if a 180f thermostat sits a couple of degrees cooler than 180f. This is where you might want to adjust the tune to ensure the timing cant change.
Really doesn't matter much which thermostat you use tunewise, and wouldn't be worth paying to get these parameters changed. The cooler one will give you a bit more time at WOT before it inevitably overheats.
Is there any benefit from running an alloy head at 195 vs 180 to dissipate heat from the engine quicker? That's another debate I think.
Edit: The motor wont get any cooler than the low speed fan off point regardless of which thermostat is installed, so there is no point getting a cooler thermostat unless you did change the fans to force it colder.