160 vs 180 thermostat

I agree with everything that RRR has to say, componets have a tendency to wear out sooner as well when they're not operating at the designed temps.

That being said, you've got to be comfortable with the car as you're driving around town. I hate the feeling of having to keep one eye on the temp gauge and the other on the slow moving traffic ahead. I think part of the problem is that you may have poor air circulation within the engine compartment. Dropping in that behemoth has reduced some of the effective area that would allow for airflow and dump some of that engine heat.

I once had a 30' 5 window coupe with a big *** engine in it that was tightly cowled and had the same problem as you. I tried a lower rated t-stat which helped, but eventually took the cowl side panels off and that solved my problem. Dump the engine heat in a tightly cowled engine will help the cause, especially in stop and go traffic. Hot rodders would cut louvers in the hood to help facilitate the problem, but I wouldn't expect you to do that.

I'd run it as is, you can always swap in another t-stat if need be.

Great looking project! I'd love to see the whole car.

95* in Hayward? Eww!