I am pretty sure we are going to hear that the book offers no solid confirmation on the chassis number. I am not sure we can, but I think that if we could somehow determine that it was #04R photographed for the book, that would make confirming the 'M66 MCL' GTR being a repaired chassis #14R a sure thing. At least until we can get eyes on the chassis plate.
Certainly it appears to me from all the evidence presented here so far that it must have been #04R that stood in for #14R in that last race, making that strange entry on the Chassis History poster surprisingly correct! In fact this is the first time in a long time I've had this much confidence in that little notation.
>8^)
ER