The people that do steel boats and compasses better than anyone else is the good ol' UNITED STATES NAVY. I'm near San Diego so that's what I would do....start looking for some surplus equipment rather than brand new store bought.
N.E.W. = Never Ever Worked.
Yes! I will be interested to see how you make out with the vacuum approach. I never tried that because I was taught "my" method many, many moons ago and it's quick, dirty and effective with no moving parts and no electricity required.
One thing that makes me think you MIGHT have difficulty with, using that method, is that the return line goes back to a higher fitting in the tank and you will undoubtedly be pulling on that line as well as the supply side. So...physics being what they are...the "path of least resistance" comes into play. It makes me wonder if your vac pump will just pull in air from the tank.
But, with the RESTRICTED FITTING in there to slow things down....I don't know. Only ONE way to find out!
AND if you are intending to, indeed, refill the tank before the attempt....that will help immensely.
As far as the pickup tubes go...it is usual to find that the tank will be constructed with a small "pan" area that presents a low spot for the pickup to pull from. This is not always the case though and, even with that, you might suck air because of a wake going through the docks and causing the fuel to slosh a bit. It only take a second to pull in an air pocket. So, finding the fuel level as low as you did probably indicates she just sucked in some air. But, do take note of that level you have in there now and you will know just how low you can go. Wouldn't want that to happen again coming in to a marina or off the bow of a container vessel!
The injectors are lubed and cooled...somewhat....with the fuel too so keeping it as high in the tank as is feasible is always a good practice.
That 12v71 is one ROCK SOLID engine! That engine has probably moved MORE DIRT in this country than any other. CATERPILLAR is likely STILL trying to catch up with the yardage of the old TEREX earth movers with the 12v71 in the front and 6v71 pushing in the back. And they haven't made any of that stuff in DECADES! If she starts (with fuel of course) easily and idles with little to no smoke....your crate engine story may very well be true. And, if so, you should get a WHOLE bunch (thousands of hours) of trouble free service.
Let us know how it goes with the restart.