73' B3 340 Duster pro touring build

Whats the purpose of the cowl anyways? I want to get rid of it and I will not have AC or Heater. The only thing on the firewall is the brake cylinder

It seem there functional purpose was strictly fresh air thought the floor vents at your feet. The only reason I'm keeping mine is strictly cosmetic, I want everything the factory put there to remain... but want it to me modified or updated with a modern look.