Old Caterhams- what to look for?

[scubadude]

My goal is to build a Caterham but at the moment time is short but having recently seen a few 2nd hand ones wife and I are considering "scratching the itch" to see if we like it medium term before committing to a build.

Seen ones between 2 and 20yrs old, obviously I understand the mechanical differences and what to look for, anything on the chassis, body and interior side worth paying close attention to on old/high mileage cars? (by "high" I mean 30K+ miles on a Caterham :-)