One thing you'll find when running a top is that you'll need to weatherstrip the doors.

Tops create a low pressure area in the cockpit and suck in air from the outside.

If you have louvered side panels - in my book they're a necessity, and no criticism of your car intended here - the hot air from the louvers comes in the door gaps.
More in the front vertical gap than the back, but at highway speed there's quite a bit of hot air coming in.
Airflow out of the side louvers is 20-30 degrees over ambient at city speeds.

A cowl air vent helps more than most think.
It's a real boon on a hot day.

Putting a cowl vent on the 31 is on the list of things to do....