OK it's a 1 & 3/4 inch SU (44mm)
It sits at an angle of 30 degrees.
I bought it from a vintage car specialist, rebuilt and to my specs.
He supplied an air filter adaptor which I used to make the cannister you see in the photo.
I opened up the intake to one big hole and used a stainless steel bend which I squashed at one end to match the intake hole.
A couple of plates cut to suit at each end and I had a manifold adaptor.
I relocated the airbox a few inches forward to allow the cannister to mate up.
Made a new throttle cable. Le Voila! A carb that allows great performance and NO flooding due to the float bowl being beside the main body of the carb.
With these carbs the main jet is matched to the carb, all you change is the needles. ( just like a motor cycle carb needle) These are available in a myriad of tapers and allow simple tuning.
Single throat means no balancing of duals.
And the choke is a main jet enrichening device which means no venturi obstruction with a choke butterfly.. When the main throttle is wide open it's almost a straight tube to the engine.
As I said, simple, efficient, and (almost) foolproof.
No vacuum hoses, switches, funny little doodads and tiny passages to get blocked etc.