Since the fuel comes out of the pump and goes as far as up to the carb, and no further, there must be a blockage there. That is, a problem in the carb.

I know this sounds obvious, however it's not to be overlooked. Be certain that the needle valve is open.

If it is open, why not disassemble the carb and look for debris which is blocking the fuel flow?

Also, when you reassembled the engine, did you get the timing correct? It will not draw fuel, even if the needle valve is open, if the intake valve is opening when the piston is on the upstroke.