Oldish thread, but I wanted to share some of my preliminary research on this topic.
This swap seems pretty feasible if you have a wrecked Tesla available to you, or if you have about $16-20k for Tesla parts alone. It's not easy or cheap, but it's definitely not impossible. Some obstacles will include converting the rear end to accept the Tesla rear subframe. Several people have put in Nissan S13 and S14 rear subframes on their S30s, so a Tesla rear subframe is not impossible. See my attached pictures to see examples of a Model X and Model 3 subframe with motor and complete rear suspension. You'll pay in the neighborhood of $4k for a Model S/Model X rear assembly, and maybe $10k for a Model 3 rear assembly. With those rear assemblies, you are reducing your moving parts count by lots. Tesla drivetrain omits the following:
water pump and coolant system
pulley driven air con
timing belts / chains
ignition systems with spark plugs
fuel pumps and fuel regulation
fuel tank / cell
exhausts / mufflers / emissions control devices
The Model 3 has a very advanced modular battery array compared to the S and X. In the 3, Tesla situates them all in a row below the floor and they each have integrated circuitry. The S30's floor isn't long enough to place a stock Tesla Model 3 array in. If you have half a million dollars, maybe you can buy a Tesla Roadster for parts 😅. If you removed modules from this array, you'd still also have to raise your S30's floor by at least 4 inches. Or. you can reconfigure the array and have the modules line your engine bay and the hatch area. There's also the transmission tunnel which you'll no longer need, which you can widen at the rear to facilitate the storage of several battery modules. Currently, complete battery arrays from wrecked Model 3s are in the $10k range. Check out Jack Rickard's video of a Model 3 teardown:
Some people are creating their own LiIon battery arrays, but the Model 3 is truly next generation stuff with great longevity and energy density Lastly, you'll need "engine management" ... it's territory I haven't researched heavily, but a good start would be checking out EVTV Motor Verks and EV Controls, neither of which I have any experience or affiliation with.
Basically, you can put pretty much anything in a Datsun but getting it to work (reliably and safely) is another story. I have two Tesla PowerWalls for the house, but I definitely don't have $10k for a battery array for the Datsun, so I'm just roll with the S14 subframe that I already have. I know EV swaps are inevitabie in the near future, so I might save the Tesla dual motor swap for my Land Cruiser.
I know some people ask "why do this?" Once people have ironed out all of the wrinkles, good battery tech comes down in price and charging times are reduced (graphene batteries and supercapacitors, perhaps), the performance potential and overall simplicity make pretty compelling reasons. Also, if you generate your own electricity, even better.