Remove the fuel pump and remove the fuel pump mounting plate. Remove the fuel pump rod and inspect it for excessive wear or damage. If it checks out okay, reinstall, disconnect the hot wire going to the distributor, and have a buddy bump the engine over while you keep your finger on the fuel pump push rod, If the lobe on the cam is still good you'll feel the movement of the rod. If the rod has little movement then the lobe on the cam is history.
When you find the issue and your ready to reassemble remember to lube the spring cavity of the fuel pump with cherry or moly lube before installing.