A lot of cars for motorsport use had vents on the side, TR4s, Big Healeys,...
Spitfires as well. For rallye and on the Le Mans cars.
And as important, as to get the cold air in, is to get the hot air out (airflow.)
Alternative Spitfire bonnets have got characteristic vents on the side.
But to achive an effective airflow is problematic.
Different order of battery and fluid cylinder by RHD / LHD cars.
Easiest way with LHD is to remove the wiper-motor.
RHD cars have got less free space between the battery and bonnet.
Most effectivly would be to start with a RHD car. Transver the battery to the rear.
Side effect, every gramm counts to move from the front over the rear. axle.
Problem with the windscreen wiper motor blocking the airflow is known. But even Spitfires racing at Le Mans had the windscreen wiper motor.
It is fairly easy to move it inside the cabin. or at least use the smaller one from a TR.