Hi Dale,
the Spitfire Kit does not have the original Layout of the Spitfire.
It is in 1:5.2 but there are some mismatches like size of the Battens etc.
If you are looking to US sizes here is a website with Original Boats which are APBA registered.
Original Plans
These plans are converted from Foot/Inch etc to Milimeters and then into 1:5.2 Size.
You might have it easier to convert only the Original Sizes to 1:5.2.
If you need Material you can have a look to
US Shop
I believe here are several people intrested in the Original Sizes (if possible in Milimeters) of some of the Vintage Motors.
For example the Mercury Super 10 Hurricane (Build from 40 until 43)
The original Spitfire was equipped with that kind of Motor.
Thanks and have Fun
Heico