it appears the problem preventing you from installing a larger air cleaner is the large line that exits up and over to the brake booster. see if you can find a tree where all the "branches" are perpendicular to the "trunk". my 70 has a tree like this on the intake manifold with just two horizontal branches. one small one is capped off. the other large one goes back to the real "tree" on the firewall. from there all the vacuum is distributed to the rest of the systems that require vacuum - booster, headlights, trannie, heater/a/c control, etc. your "tree" that has the large line exiting out the top of the tree vertically is bogus. see what you can find from West Coast Classic Cougar website.