unusual features on orphan

[cmj]

How does one document unusual features on an orphan automobile? Especially when there is no other one like it existing. My car has features not found on others of its make,like chrome on intake side of intake/exhaust manifold. Balance tubes not found on others of same make, chrome tappet covers. all appear to be original. last owner had car 30 years and was that way when he purchased. Car was an export version and thus was R/H drive etc. Intake/Exaust manifold look to be an export item only,different from state side cars