I would really like to believe that there is no reason for story fabrication but that just isn't the way it is. From "driven only on Sundays" to "previously owned by (insert famous person's name)", I would like to think I have heard it all. For that matter, my car was the first S30 in the State of Florida. Just ask the brother of the previous owner's son. Perhaps it was raced in Japan. I have heard many stories about servicemen racing their newly purchased sports cars in amateur events. Generally speaking, that's the sort of thing one wants to stay away from when considering the purchase of a used car. You know; the abuse and all. I don't know quite what to think of the LHD conversion. Plenty of RHD cars made their way into the U.S. The guy down the street from me in 1971 came home with an RHD Fairlady. It was yellow and had headlight covers. I just can't imagine why someone would go to all that trouble and, of course, the question has come up concerning from where the donor parts came. I would bet that the conversion happened after it was imported and that the car has seen major work, parts replacement, and previous owner stuff.
None-the-less, the car is unique and appears to be in nice restorable shape. Considering the unique configuration of components in the car, I think you have a lot of latitude for your restoration while still remaining "on course". Have fun and enjoy the ride! Screw the history and let the project be a testament to your automotive skills.