When I decided to drop my crate 351W thermostat from 180 to 160 I first called Ford Racing Tech line. They advised the 160 would be just fine and could improve performance, not inhibit performance. This with a carb, no computer and no heater.
I use
synthetic oil and 160 engine temp is more than enough for our modern day oils to lubricate properly. The most motor wear is in the first few minutes not at operating temp. My 351W motor still runs in the 175-180 range in the summer and can even reach 185 range on hotter days but the thermostat is at 160. On coller days it levels out at 165-170 degrees. I have read artricles where carb motors have run better on the dyno at 160. Certainly EFI computers get confused with Air/Fuel ratio and a heater is warmer at 195 than at 160 degrees but each motor is different.
I agree if you pull your thermostat out you should NOT leave nothing but should cut out the center to slow down the coolant flow for proper radiator efficiency. I also learned that trick from Southern Automotive from a prior BB Cobra I owned. That 390BB seemed to run hot with ANY thermostat yet ran at 180 with the center punched out ! Cannot figure but it was the case! With a carb and a heater, if used, I would probably go to the 180 degree thermostat.