If:
- the valve plate is nice and soft and fitted right (the mechanic checked that did he?),
- and the fuel regulating valve does not stick,
- And the (also soft) regulating membrane can open the regulating needle on fuel demand (right way up, with the metal disk inside)

it should pump if you bump the prop to and fro against compression while closing the choke.
If not, there is a blocked passage or the internal strainer is clogged up.
If all fuel passages in the carb are present, A thoroug cleaning of the carb should cure any blocked condition, and then it should pump. The gas line is fitted to the nipple in close vicinity of the cast cover isn't it?