I stumbled into this R381 model on my first trip to Japan in 1992. The R381 was a little-known wannabe Can Am car Nissan built only one of. There was something of a tradition of one-off cars like this, going back to Prince Motors in the mid '60s.
Several trips to Japan later, I managed to talk my way into Nissan's secret warehouse outside Yokohama where they store all their old race cars. Sure enough, there was the real deal:
This series of cars went back to the Prince R380, built just before Nissan took the company over in 1966. The Prince R380 got "Nissan" painted on the side of it, but little else changed.
Then Nissan built the R380II (red and white in the background below), this R381, and finally the R382 (just the blue and white nose is visible under a plastic cover) before they stopped the series. The R390 (black/red behind the R380II), built for LeMans in the late '90s and actually produced in incredibly small numbers, was a spiritual continuation of this series.
As you can see, there are some differences in the markings between Tamiya's art and the real deal. Especially the fact that the real one says "Datsun" while the model says "Nissan". Most likely, it said Nissan first. I believe the car may have traveled to the U.S. (without a transmission, if I recall correctly, so nobody could crash it) on a PR tour at one point, which would explain the "Datsun" label.
All of this is a long way of getting around to admitting that I'm never going to build this model, and if somebody else will, they should buy this kit from me. $40 + shipping.