Yahoooo! Nailed down the problem finally!

It seems that the carb spacer block was mounted properly, but there are two holes on the rear mounting surface of the carb and only one is used as the pressure/vacuum signal hole for the fuel pump. Well, I had the carb mounted with the wrong hole lined up with this port, and hence no fuel was being pumped.
On the down side, the low and high speed needles are facing down and to the front (propeller), so adjusting the mixture is a bit dangerous and must be done very carefully.