There are a number of non-FIA racing series on the continent where a non-FIA car is welcome. I'm no expert on Bs (hence the screen-name!) but late Midget shells can be "restored" to earlier spec sympathetically by removing the internal bumper strengthening, and other details are not extensive enough to cause a problem.
Pieter Bakker will doubtless be along soon with details of his Legendary Circuits series which comes highly recommended:
http://www.fisc-eurotour.org/Legendary-Circuits.html
Have fun!