[Moppie]

Hmmm damn tricky one that.

I have heard of them, and seen a few pics, but have no idea where they came from.

However simply due to the unpopularity of putting Carbs on a B16a they could be quite hard to find.

Have you tried a manifold from an old B20a from an old Prelude?
Might be very similar? I was compareing a mates Si lude with my car the other day, and things like the throttle body look like they could be easily swaped. (same bolt pattern, but differnt TPS etc)

Otherwise you might have to find someone who can make you a custom one? or even make your own?