I like my engines like I like my coffee- hot.
For one, the 160 T-stat thing, IMO, is a waste of money for the street. For one, hardly anyone does anything with the rest of their cooling systems to make the T-stat work in that range. They just pop it in thinking it's going to solve an over-heating issue. The cooling system does NOT care. It should open at or around the 160 deg F mark, and close if it's under that. What your engine does with that is up to how it's built and if you changed anything on the system to take advantage of it. If your system was running 200-210 before, tossing in a 160 T-stat by itself won't make any change in that except to be a flow restrictor because it will be open most of the time.
As previously mentioned, controlling the fan temp on/off is a big player in helping keeping things cooler when using that 160 because you're trying to move a cooling medium. But it's still not a panacea. And especially if you're running old-school and have a fan clutch instead of electric fans. Those things don't even engage until coolant temps start hitting the higher temps. There's so many variables that can affect combustion temps and coolant temps. From RPM changing to fuel mixtures to pump design, coolant flows, and air flow through the radiator (and also out of the engine compartment)- all that makes a difference. Couldn't tell you how many posts of frustrations I've read about someone changing out their radiator only to find out their cooling problem didn't go away. A lot of times, it's not just the radiator causing the issues.
Delta T and flow rates are the key. Over the years taking courses like heat transfer and fluid dynamics has opened a lot of eyes to how coolant systems actually work. I know it did mine. Additionally, working at a nuclear power plant gave me access to steam generator engineers who's entire life was about heat exchangers, cooling systems, and metallurgy. Talking to them was challenging because those guys lived on a different plane of life. But they always were happy to answer questions about stuff like that.
There's a reason GM chose 195 T-stats for most G-body applications and that's fuel efficiency and subsequently, lower emissions. They just put in bigger engines (I know, laughable) or added a turbo if they wanted more power. Faster warm ups, higher engine temps, CCC, thus lower emissions= happier Feds. Parts book doesn't even give you a choice. Darn near everything is 195 except the turbo Buick, which is 180. GM part number 3041390 for V6, and 3051139 for V8, 195. (3054228 for 84-85 Turbo V6, 3037745 for 86-up Turbo V6)
Can you get by with a 180? Sure. I had been using 180s in most everything since I started working on cars. The only real problems I had with 180s is when they didn't work right. That's why you should test them before installation regardless of which you choose. I've caught 2 in my life that were dead right out of the box. It's not fun changing a T-stat twice because you didn't check it first.
This is all JMO, so take it with a grain of salt.
