USA history of XK140 FHC wanted

I have recently bought a 1956 XK140 fixed head coupe and I am
trying to fill in the missing years it spent in the USA,
from circa 1958 to 1994. I hope someone out there can help.

Here is what I know of it's history. It was sold by
"Hatfields",a dealer in Sheffield, England, in April 1956. It
was right hand drive, British Racing Green in color with
suede green trim, registration number "RWY 725" . The
chassis number is 804644.
I understand,around 1958, it was imported to the USA and
was supposedly, at some stage, owned by the President of
Xeon Oil who raced it and at one point had it driven by
Grahanm Hill (all unsubstantiated hear-say at this stage).

The car was imported into New Zealand in 1994, with the ride
height set very low (which may give credence to it having
been raced). It was now Old English White in color and had a
3.8 litre engine in it ( with out any engine number on it), with 2" H SU carburetors, Disk brakes all round (?XK150) and (going on the head number "W 9376-9") an ''A'' type head off an XK120.

I am about to start restoration of the car but would like to
fill in the gap of it's 36 year history in the USA if
possible. The thing that may help identify it is that it has
always been right hand drive. Any help anyone can give would
be greatly appreciated

Thanks

Peter White
New Zealand