Remember, the late 70s aircleaners are set up for 3" flex tube already, so get 2 of them and put the snorkel from one onto the other. I did that with my 77 Cordoba when I was 17 (gosh, 20 years ago!).

Didn't notice any performance improvememnt, but there are lots of jetting, etc variables to investigate (which I didn't know how to do back then).

There’s an Aussie magazine website that did some investigating on this regarding using a pressure gauge and tubing at the front of the car to determine optimum placement of scoops. Do a search for ‘negative pressure supercharging’ or something like that.