Based on your description of the issue you are experiencing. ...is this a good summary? ... This carb RAN on this engine at at idle. Then something changed, you took it off, cleaned it, did some fuel system confirmation and now it will not use gas from the bowl. Did you partially rebuild it or use new gaskets? Something changed and that is what I would be first looking at to establish a starting point. In my recent adventure with a mono jet Rochester, a new fuel pump was my problem....pushing too much pressure and creating flooding that made me think my carb work was suspect. I went back to the beginning after several carb tinkerings and finally checked the "NEW" part and found the problem.
Whatever you did from running to not running should be reviewed. Seems like your description has the carb isolated as the engine runs when you hand feed and bypass the carb. I wonder if you start it with a helper with fuel and immediately go to revving off the idle circuit and will the accelerator pump try and let it run to narrow down the potential problem? Otherwise if that carb won't allow any fuel through it, not enough vacuum ( massive leak) or blocked carb passage? I would think it would have to be a big vacuum loss to not allow ANY fuel to be drawn down and evident. If you are fairly certain of vacuum, that carb has to be really inspected taking nothing for granted with just passing air through. Good luck.
