When was that? Probably advertizing because they wanted to promote the new "Swirl Port" head (Nineties?)
In stock form a 302 flows worse than a stock L or X head. The EQ on the other hand is a different story.
Well yeah, the 302's in stock form have the smaller 1.78/1.50" valves and 318 ports, so, you can't compare them to X or J heads which never had anything smaller than 1.88/1.60" valves and had the larger 340/360 ports. You can compare the 308's to the X and J heads, and they're about the same on the intake side. The exhaust side is where the "swirl port" heads are better. The 302's are only interesting because they have closed chambers (308's are open chambers like the X and J heads). They're a nice improvement in compression when used on a mild 318, especially considering how low some of those engine are for compression from the factory. But if you start modifying stuff they're still a 318 head, you need to add bigger valves, port work etc and by the time you've done that you might as well have bought an aftermarket head nowadays, you'd have no more money involved and you'd have heads that have a lot more potential. 302's are really only a worthwhile upgrade if you're planning on bolting them on in fairly stock form (unless you can do the machine work yourself), and it's really just about the increase in compression, not a dramatic improvement in cfm for the heads. They were a lot more interesting/useful before there were a bunch of different aftermarket heads available like there are now. Better to just buy a set of EQ's, or even stock magnum heads for a mild build now. Smaller chambers AND bigger valves and better flow.