I also have a California car with the closed CV system and 90 degree fitting on the air cleaner that's connected to the valve cover breather ('67 Mustang). I prefer the closed system, because every car I've had with an open breather on the valve cover, it's been messy and required constant cleanup to keep that area clean.
My biggest concern was the tiny sliver of space around the base of the air cleaner that was the only way for air to get into my carb. I know it's a little one barrel, but my air cleaner had no snorkel or hole, just a 1/16 to 1/8" (depending on the dents around the housing) slit around where the top meets the base. The first thing I did was to drill some 9/16" holes in the base, outside of the filter element, to allow some air inside. This is still sucking in warm air coming right off the top of the engine, but I figured it was better than before, and it's an undetectable modification while the air cleaner is in place.
I really like the look of the Scott Drake "HiPo" style air cleaner made to fit our little carbs, but there is no provision for a breather hose. I have a friend who has one on his car with an open breather, and of course, the area around the breather is constantly oily. I bought a 5/8" 90-degree brass elbow, drilled a hole in the base of the Scott Drake unit, and mounted it in there secured with panel adhesive. I crimped a section of hose on top of it for extra stability, then ran a 5/8 PCV hose from a different year/engine size Mustang from the fitting to the breather. It's a pretty stealthy setup, and allows me to keep the closed breather system with the open element air cleaner.
Yes, before anyone mentions it, I know the rest of my engine and bay looks like crap. When I redo my radiator and exhaust this winter, it will get a makeover. Hope this is helpful to anyone who is considering a similar setup.
