If you want it reliable, do not mod it. A reliable Datsun is a stock Datsun.
If it has been sitting for ten years, drain whatever is in the gas tank.
Again, if it is stock, a stock alternator will work fine.
The brakes do not self adjust, you must adjust the brakes manually, at least every oil change.
Disconnect the fuel line, if you have not yet cleaned the gas tank.
First, I would do a compression test. Now I know a compression test should be done on a warm engine, and if the truck has not ran, the engine will be cold, but a compression test will let you know if tinkering with the carb or ignition is a waste of time. A L-16 should have a minimum of 159 PSI, with less than 10% difference between cylinders. If compression is a little low, adjust the valves, and check again. Put a little oil in the spark plug hole, and check the compression.
Next check the ignition system. Pull the coil wire off the distributor cap, and it should have a blue spark of about 1/4 to 3/8 long. Set the ignition timing to 10 to 12 degrees before TDC.
Does the cooling system hold water? If so you and run the engine for a while. If not, you can run the engine for a short time, about 30 seconds or so, but not much longer. Fix cooling system leaks.
Got compression, and ignition? Pour a little gas down the carb, and see if it will run briefly on that. If it does, clean the gas tank, or get a small gas tank from a old lawn mower or something, and hook that up to the fuel pump. If you do get a small gas tank, you can hold the tank above the engine, and gas should flow through the fuel pump by gravity, and fill the float bowl on the carb. When the carb is full, operate the throttle a few times, and see if the accelerator pump squirts gas down the primary throttle bore. If the accelerator pump works, try to run the engine on fuel from the small gas tank, or on the clean gas tank in the truck.
At this point, I would change all the old rubber fuel system hoses, they are about 50 years old.