That kind of looks like one of those box-style NASCAR intakes, with a custom top to mount the carbs. Usually on those manifolds the tops unbolt, and you can replace the top with a machined aluminum plate, allowing you to put any carb combination up there. Having said that, I've never seen a NASCAR style box intake for an SOHC; it may be that the entire intake is fabricated, not just the top. I like the way the LeMans float bowls were used on the 2 barrel carbs on that setup; along with the magneto it makes the engine look very period correct.