Reading the whole thread through I see you have already cleaned the fuel lines. I would check all fittings are tight.
If, as you say the pump is rebuilt, check all the screws are tight on the pump and before you install it you can test it with a little fuel and pump it into the bowl. (this will all come out as you manipulate the pump into the block (in my experience also)
In my own experience using the hand primer on the pump is next to useless. As someone previously suggested, pouring a little fuel (probably about 1/4 of a mower tin lid's worth)into the carby should get the engine firing.
If the engine fires with this method, (and it should) then you need to do this about five more times to get the pump to suck up the fuel from the tanks. It does take a bit of effort but I have to do it with one truck I have to get it running.
A Landy engine will run with stuck valves, so focus on getting it running before you engage in full surgery on an engine trying to fix a minor issue.
Cheers,
Ian
