I'd agree completely that for performance with the basic foundation of more cc's and the 44mm intakes the twin SU's would (should?) be the answer--but this fellow doesn't seem to be after balls out performance--otherwise why the interest in the A cam and running on skinny tires. Looks like he's after low rpm torque and a single carb would provide the throttle response he's after. I saw from his profile that he is in NZ. Dual SU/Stromberg manifolds may not be readily available to him---and shipping may be cost prohibitive. While the single carb route may be counterintuitive to our way of thinking it may just be what he needs to fulfill his expectations for the car.
I think we may have gotten spoiled here in the USA with most of the carbed cars coming in with the dual set-up. We're just used to it. Poster JJ in South Africa (recently posted photos of his 544 engine bay) fruitlessly waited a long time for a manifold to be shipped and I was able to help him out with a spare I had around so he could complete his project.
I envy your twin DCOE set-up but feel I made the right choice with a pair left over from my Alfa Romeo days. Rather than keeping them I found an Alfa owner happy to give them a new home. -- Dave