Go to the auto parts store.
Ask for a 180° thermostat that fits the stock application. If they don't know, go to another parts store that knows how to 'fit' them. Make sure you get the rubber seal AND paper gasket.
Go home with the innocent thermostat and whale away at it with a drill (two 1/16" holes if you live in a climate like me, four 1/16" holes if you live in Nev, Tex, Southern CA, etc).
Or go to www.zzperformance.com
and let them do it for you.