I managed to put one of the NWSL flywheels on without it slipping. The only tubing I could find was Vacu-tite 47417 Hard Emission Tubing. Appears to be 3mm ID and 5mm OD (the package says 1/8" OD), it snugly fit onto the 1/8" motor shaft and the 3mm gearbox shaft, I haven't noticed any slipping. When I asked for #0 Toyota tubing I got blank looks at the 3 places I went.
I powered the engine up and didn't notice any "noodling" of the tubing and the noise has reduced. I pulled 4 cars around after putting the boiler back on and all seemed well, even had it up to 60mph!