Found my dads original 1971 duster!

I drill three 1/8 holes in my thermostat to prevent air lock in system. Another benefit is you can top off coolant system without running engine. Down side is very slow warm ups in cold weather.

I run a spring in my lower hose too to prevent it from getting sucked shut.

I recommend a180 degree high flow thermostat. I run a FlowKooler water pump too. I run Mopar Performance clutch fan..With stock recored radiator I can drive around 100 degree days with AC running and coolant temp stays under 200 degrees.

Fan shroud comes into play low speeds or idling.

You should have a hood to radiator support seal on your hood so as you drive air gets routed through radiator vs air flowing in between hood and radiator support.