Nothing wrong with the original pump. Did you fit a new diaphragm? They can crack with age and use.
If you fit an electric fuel pump, fit one with the correct fuel pressure rating. In this case, low, 2.5 to 5 psi. Trying to tame a high pressure pump with a fuel pressure regulator is not a good idea. Fuel pressure regulators are fine for triming off a few psi. Commonly available rotary fuel pumps from Carter and Holley are really, really noisy and have too large an output -- unless you have a 426 hemi shoe-horned in there.
Fit a safety shut-off circuit!!! You do not want the pump to keep running if you are in an accident!!!