It's dam nigh impossible to replace the doors, the hinges are totally different, and PH1 doors (and the holes) can be of spurious sizes. No, the bonnet vent and headlights show this is a PH2 so it really can't be #30, it has to be #250 or higher.
My old Phase2 (#278) has the Wincanton order (showing the body number) bonded into the GRP in the centre of the roof, inside the car, under the headlining. I guess this was probably the last job as the completed body left the mound.
In the absence of paperwork, or an original body plate, this might help!
The Warwick (#15) also has the body number painted there, although no paperwork in this case.