Your ideas great.

1). I am not sure if what I see is intantaneous squirt. Just wondering which direction the jet should be facing. Mine has the slanted side facing upwards (it's like a flute tube slashed diagonaly - you know what I mean). The fuel therefore, touches on the Venturi before dripping down.

2). The manifold Vacuum leak is possible because the openning is just around the loose (too free) shaft.

But why does it pick-up when I step on the accelerator SLOWLY?

DodgeMan said "If your engine is stock, then do not change the jet sizes away from stock sizes as these are a proven combination."

Which is stock engine? Mine is A12.

There are two vacuum tubes:
1). One runs from the air-cleaner housing to the inlet manifold.

2). Another runs from the ditributor vacuum advance unit to the side of the carburator.

Is this correct?

Yesterday I noticed that the car is so weak on high gears. Recently when I cleaned the carb, I just set the timing to produce spark on 0% when the crack is turned by hand. I do not know if the spark is produced at around 7 degrees on 600 rpm?
Could the lose of power due to retarded spark timing.

AlphDoti
The hoses are most likely in the correct position.

The loss of power is most probably due to retarded spark.

Advance the spark to 12 degrees when cranking. If the engine makes a knocking sound under load in the high gears take it back 2 degrees then check it again.

Repeat this, retarding 2 degrees each time till the knocking noise cannot be heard at all at under load in high gears. This will give maximum power and also best economy.

Quote:By "stock" i mean a factory standard, unmolested engine. It matters not if it is an A12 or A14, so long as it has not been modified in any substantial way, then it qualifies as "stock"

The original carb was configured by the factory to give it's best all round performance. Changing the jetting just makes things worse in the majority of instances.
I'l go with Feral on the timing. The ignition will give it's best if you have a "dwell angle" meter with inbuilt tachometer, & a quality timing light. Set the dwell on the lower end of the specified range & recheck the timing after about 5,000k to make sure things are still where they should be.

Hitachi SU tech pages
Try this site too. It's listed in the "Web Links" under Tech info.
I think you have made your decision, but I'll throw in my 2 cents anyways. I'd lean toward the SU's mainly because I don't like the 32/36 + adaptor plate+ stock manifold combo. I used to have this in my car. It worked ok.
Now I have twin 38mm Hitachi SU's. I seem to get a little more power from these. I'm also still trying to understand how, when and why they work. But they do work and I know they're not in tune. I haven't check to see if they are in sync for over a year and the damper on one doesn't feel as stiff as the other. Did i mention the homemade linkage with no way to adjust each carb without disconnecting them? How about the 34mpg?
So don't worry about these things not being perfectly in tune. You can mess up the adustments on a 32/36 just a bad as you can an SU(type) carb.
I think 2 38mm openings feeding air/fuel is better than a 32mm and a 36mm opening that gets necked down by the adaptor plate on a tiny stock intake.