Norm, that's neat to see your cold-air intake project. Looks like you've thought it through well and executed it cleanly.
I experimented with a similar system last spring on my SU-equipped L20B. I made a sheet-metal box that fed the air into the "top centre," between the two carbs, by means of a HVAC duct fitting. Flexible furnace ducting (4 inch) for the tube leading from the headlight socket. I thought it looked alright, though naturally opinions on such a matter could well vary....
I only ended up using this system for about a week though because I found that the "forced induction" aspect weakened the AF mixture drastically. It was fine at very low speeds but, if I recall, already at about 30 mph the mixture just weakened right out (according to my AF gauge). The faster I went the worse it got. I was pumping way, way too much air into the motor for the carbs to keep up with. And since I was already fighting against an over-lean mixture at highway speed, this was a further complication that I just didn't want (or know how) to deal with.
So I went back to my original pancake-type K&Ns and re-installed my fourth headlight. I've still got the airbox though and am thinking about trying again-- actually, with a setup more like what you had until now, I think. That is, I'd let air come in through the headlight opening-- but instead of forcing it all into the air box, I'd keep a gap between the two. The idea would be that the carbs would be able to suck all the cold(ish) air they want, because there's a good supply of it right there, coming right at them through the headlight inlet. But they wouldn't be forced to swallow the entirety of the supply. They could just suck what they want-- not a pressure feed, but an as-needed supply.
Anyway, I haven't tried this approach yet... and it sounds like you maybe haven't tried yours yet either. It'll be interesting to compare notes at both ends (though it will likely be at least a month yet before my car is back on the road, winter being what it is up here).