Just a little more follow-up on this to explain my opinion on not using the 160, staying closer to the 180 degrees goal.
I ran two FE cars with 160 thermos for a couple of years. The first one had iron heads and the second had alumimum heads. After running two Cobras with FEs since 1998, I feel I have enjoyed a fair time to evaluate both and zeroing in on very slight differences. Your brain becomes tuned to the slightest changes. On the second car with aluminum heads, here I was chasing a problem that I thought was carb jetting and hearing what I thought was loose valvetrain at times. (expand contract yo-yo affect with new aluminum heads combined with solid lifters). After many adjustments and carb tuning, the real "root cause" or problem turned out to be running the engine under the proper operating temp on cooler days. At 165 and 170 it ran okay, but right at 175-180 - Wallahhhhh! After two years when I went back to the 180 thermo with the steam hole...All the sudden throttle response picked up, quicker, and you could hear a little more pop in the exhaust, with an increase in power. Try this in winter time, you'll notice a big difference. As for hot summers, see the above. Good electric Fan(s) are a must in these cars, and especially in traffic.
