I would go back to the starting point.
Totally clean the original carb. Even to teh point of taking out the brass mixing tube that is located in the center of the throat.
Clean everything spotless. Run a fine wire thru every orifice you can find. Then spray carb cleaner thru every orifice also.
With float bowl off, check for fuel flow by hooking up the fuel line to the carb. You should get a steady flow of fuel out of the float jet. Put the float bowl back on. the drain screw should be on the right side. It is possible to install the bowl backwards . If you do install it backwards ti will force the float closed. (been there, done that.)
Reinstall carb and you should be good to go.