The tiny hole you found is the pilot jet, I guess, no wonder you had a hard time to start the thing. In my last photo above it is deep in the large countersunk hole and the jet gets fuel from the drilling from the bottom of the jet block, in my second photo right next to the 30 T . These pilot jets are known to be blocked with crud or corrosion from E 10 fuel. It is a mess to clean as you have to knock the jet block out of the body.
You may be right about the step on the float needle, in my case that was minimum 15 years ago - so I don´t remember. Some needles just got grooves and a clip shoved in to locate the float. No big deal anyway to do a mod with funny float chamber positions. You see the "downdraft " carb plus float chamber. Should not be allright like this with the float but no troubles from the angle as the float - ahh, floats and so got no weight on the needle - but looks weird . Did not care to find an angled chamber so far.
And yes, I went for a thin o-ring around a turned down fibre washer. The rubber is a better bet for sealing imperfections in the carb bottom.
Vic