No, it's more than a theory. I'm making a case for Justin Murphy's Nagari to be B8/46.
When previous owner, Leo Kusters, applied for FIA paperwork we made a case for him based on the car being B8/44. Our reasoning for that was that the car had come into his hands via the UK and South Africa. We were aware that B8/44 was an advanced kit (e.g. complete minus engine and gearbox) shipped to Pete Dutiot, an enthusiast in Johannesburg, South Africa. What we didn't know was that Peter had 2 Nagaris. The real B8/44 is in Spain and has been for donkey's years. When Mr. Dutoit wanted to move his Bolwells on, he enlisted the aid of Brian Taylor of "Rolo Motors" in Sandton, JoBurg, who shipped them to Chris Camp in Kent, UK. This was in approximately 1998. Chris registered Justin's car EKP 224 K with chassis number B804471, "officially" issued by BCCA-Vic. He added an orange stripe to the sky blue paintwork. A cage was built and the trailing arms changed to parallel in UK by ASD Automotive System Developments in Maidstone. Chris put the car up for sale in 1999, finally selling it in 29/12/2000 to Leo Kusters and Ab Flippe in Holland. It was exported 11/01/2001.
The FIA papers show 2 previous owners, Peter Warren of Australia and John Clince of Spain. The number B8/42 has been made up, either by Kusters or Clince. Chris C sold the car to Leo as number 44. Maybe when the 2 cars left South Africa, only one went to Chris. No-one knows how B8/44 got to Ramon Lopez' garage in Madrid. It was left there for work to be done and never collected.
Now, lets get back to Peter Warren. He raced a Nagari coupe, predominantly in NSW in the early 70s. At some stage he abandoned his first car and built up a better one. The first one presumably went overseas. In the mid 70s Peter moved to another class of racing (F2?) and sold his Nagari to Barry Main. Barry, in his own words, referred to the car as "unofficially B8/46". It is not impossible for it being "unofficial" that it was built as a replacement for the "real" B8/46. Now that opens up another can of worms. When Barry stopped racing, his race car was "parted out", with the body going in one direction and the chassis in another. Thus , there are 2 new owners laying claim to B8/46. If the "real" B8/46 is in England, that makes 3.
If I am correct in all this, Justin would have "racing heritage" in his car, possibly useful in Historic racing. He wants to register the car in the UK. He has rego paperwork showing chassis no. B8/04471 and FIA paperwork showing chassis no. B8/42, neither of which are really true.