ive seen plenty of sets of these hillman/holbay etc carbs on the bay on xflow and pinto manifolds, to be fair i think some people just dont know the difference. they do work to a fashion but not well, Escpecially at high revs. they take alot of faffing about to get to run and they are never perfect and will never return the performance of a "normal" set of tooters,due to the way they vent, the castelled spacer replaces the normal vent hole by the left venturi
This is my albeit limited understanding of them...
Just had a quick look at ur resto, and the one blurry photo showing the tooters they do look like Hillman/Holbay ones on a brighter note your car looks fantastic, credit to you