At one time a 15 years or so ago the mechanical fuel pump certification by the USCG was rescinded. Rebuild kits and new pumps became very hard to acquire.
There was concern of shore-side automotive equivalent pumps being used in boats and the automotive pumps have a vent hole that allows gasoline to drip on the road- This enabled the savvy driver to see a problem with the pump before it failed completely- Aboard a boat this fuel dripping in a closed engine compartment would be a fire hazard.
That issue isn't a problem with genuine marine grade pumps. There is no vent hole.
I was able to but a rebuild kit for my old pump and it is still in my spares locker. My original 1978 fuel pump works perfectly. It has never been modified except for paint when the engine was rebuilt.
The supplied mechanical pump is a robust, simple and safe unit. It features a 'tickler' lever that enables you to prime the fuel circuit in the Spring for first start up so you don't risk flooding the engine cylinders with seawater while waiting for fuel to arrive at the carb at first crank- This is also helpful if you don't use the boat for a month and the fuel in the float boat evaporates- A quick couple of 'tickles' and the carb is full again and ready to start immediately.
We had some lousy HOT weather this season so ALMA sat unused for a couple weeks- That tickler enabled me to start the A-4 without shutting off the seawater intake and risking burning the cooling pump seawater impeller.
I would recommend you stick with the original fuel pump. An electric pump cannot be repaired, requires an oil pressure safety switch to prevent pumping fuel when the engine isn't turning, a fuse and busy wiring. That's at least 10 wiring crimps and lugs all of which can fail from corrosion usually at the worst possible moment.
The 'fresh water cooling' kit was about $600 20 years ago. It has performed flawlessly. The heat exchanger has been cleaned and painted several times and works perfectly.
Having a boat sailed in Fresh Water has saved your Atomic Four from internal corrosion.
A 'fresh water cooling kit's anti-freeze is even less corrosive than lake water and the big bonus for you is a hotter running engine that is more efficient and longer lasting. Again watch out for the 180 degree water in the shower and sink taps- Another bonus is a 6 gallon hot water tank will give long luxurious showers at 180 degrees.
Save the money for the electric pump and get a (pair) of Pertronix electronic ignitors. You'll want a spare.
You'll also want the matching Pertronix ignition coil. I got good deals on eBay.
I do NOT recommend the "Hot Spark" brand ignitor. I have had them fail in cars and boats. Their customer service is abysmal.
I love my PYI dripless stuffing box gland.
Originally (20 years ago) I had the original "low-speed" version and I needed to 'burp' the bellows every time I went sailing. In saltwater the same organisms that die and make sulfur smells in the head create sulfur gas that displaces the water within the bellows and that is a problem because the water cushions vibrations and cools the friction surface in the gland.
The newer PSS shaft seals all have the vent tube that allows the built up gas to escape and there is no need to 'burp' the bellows. My new one has worked perfectly this first season with the new engine.