I deleted a photo of a cowl induction mod that was on a big block 64 Dodge Polara that was for sale near me last month. They took a dual snorkel air filter assembly and removed one snorkel. They welded an oval shaped duct to the where the snorkel was and it's length was about 4 or 5 inches short of the firewall. They had a similar piece of ducting attached to the firewall and a short span of flexible rubber joining the two pieces of ducting. There appeared to be some sort of mechanism attached to to the firewall and just below duct. It appears that there was a capability to open and close the air path from the cowl in order to prevent rain from being drawn into the carb. The untouched snorkel was pointing towards the passenger side. The entire assembly was painted in flat black and blended into the background as the entire car was painted black. It was very well done. I recall seeing similar cowl induction setups on a number of cars back in the mid-1970s.