What is the diameter of the fresh air cowl vent opening?

Home stretch, and chock up another POR-15 fan! Bartered with a buddy to show me how to bend 2" wide metal around a plywood form. He also tack welded the loops in place, and I gap filled with POR paste and painted it all with POR again. This is the install looking up inside the cowl opening.
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Next up is to spray Eastwood Internal Frame Coating up inside the whole cowl area. And as long as the heater, left air box, radio, and glove box are out, I pulled the wiper shafts and replaced the seals and did that cool grease zert mod I read about here. That is after I get the feeling back in my fingers from taping off the air grill.
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